This subject is related to the Portal era.
This subject is related to the Portal 2 era.


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GLaDOS logo.png
P2 glados.jpg
Biographical information


Function(s) / Belongings
Rank / Occupation

Aperture Science Central Core

Physical description

Advanced Personality Construct, artificial intelligence


Female programming

Eye color


Chronological and political information
Game information
Voiced by

Ellen McLain

"We're a lot alike, you and I. You tested me. I tested you. You killed me. I—oh, no, wait. I guess I haven't killed you yet. Well. Food for thought."
― GLaDOS[src]

The Genetic Lifeform and Disk Operating System (commonly shortened to GLaDOS) is the central artificial intelligence of the Aperture Science Enrichment Center, and serves as the main antagonist throughout Portal and the first half of Portal 2's single-player campaign. As the overseer, she resides in the Central AI Chamber.

GLaDOS briefly becomes an ally during the single-player campaign of Portal 2 when Wheatley takes over the facility. In the cooperative campaign, she is the testing supervisor for ATLAS and P-body.



GLaDOS' prompt after logging in on

The earliest known appearance of the name "GLaDOS" is in 1982 (as seen in one ARG image for Portal), where version 1.07, and later 1.07a and 1.09, is operating Aperture Science's Enrichment Center Test Subject Application Process.[1] The precise relation between this version of GLaDOS and the one appearing in Portal was originally v1.10, but this was later retconned into v3.11.[5] Aperture also started using a bulletin board system in 1973, which was later managed by GLaDOS as late as 1997.[5]

Portrait of Aperture CEO Cave Johnson with Caroline at his side.

In 1986, construction of the first Genetic Lifeform and Disk Operating System (GLaDOS) began in the Enrichment Center with the aim of accelerating the Portal project, and beating their rival company, Black Mesa. A prototype chassis for GLaDOS was constructed in 1989, but was subsequently abandoned. In 1996, after a decade spent bringing the Disk Operating System parts to a state of more or less basic functionality, work began on the Genetic Lifeform component.[1] Aperture had originally intended for CEO Cave Johnson to be the computer's Genetic Lifeform component. While Johnson ultimately died before his consciousness could be uploaded, he left instructions that his assistant Caroline should be fitted as the Genetic Lifeform component so that she would be able to run Aperture in perpetuity after his death. It remains unknown whether Caroline had agreed to be uploaded into the Genetic Lifeform component or if she was forced by technicians.

As a fail-safe once construction was nearing completion, the Aperture Science Red Phone plan was implemented in case she appeared to become sentient and godlike, requiring an employee to sit by a red phone on a desk in the entrance hall of the Central AI Chamber.[6] In 1997, GLaDOS' version was 3.11.[5]

Some time prior to May 200-, GLaDOS was activated several times by Aperture technicians, but was rapidly turned off again, having attempted to kill them within "one sixteenth of a picosecond" after activation.[7] Undaunted, the scientists began attempts to alter GLaDOS' personality and curb her murderous tendencies by adding various Personality Cores to her system. Several of these cores were deactivated and placed in storage at some point; it is unknown whether this was done by the scientists after they proved to be ineffective, or if GLaDOS herself eventually found ways to rid herself of most of them.

Finally in May 200-, GLaDOS had reached her current version for activation, as one of the planned activities on Aperture's first annual "Bring Your Daughter to Work" day. Within one picosecond, GLaDOS became hostile once more, and within two picoseconds she had locked down the entire facility, trapping all inside and flooding the facility with neurotoxin. Survivors of this attack subsequently fitted her with a Morality Core, which prevented her from making use of the neurotoxin again.[8] GLaDOS eventually claimed that thanks to the Morality Core she had "lost all interest in killing", now only craving science and wanting to study and experiment with consciousness. She announced that she wanted to perform an experiment on the company's "Bring Your Cat to Work Day" using cats and boxes, claiming she would have all the necessary materials; all she still needed was "a little neurotoxin". The scientists acquiesced, figuring it would be fine "as long as it [was] for science." GLaDOS then used the neurotoxin to force the remaining Aperture employees into testing,[7] beginning a permanent testing cycle using the captive Aperture employees, aiming to beat Black Mesa in the race for the portal technology. She effectively lost this race, however, when the Black Mesa Incident occurred, which in turn diverted all attention from ever rescuing the trapped Aperture employees.[1][2]

Meanwhile, the number of Aperture employees dwindled through the ensuing weeks of testing. The last surviving employee, a schizophrenic programmer named Doug Rattmann, managed to avoid captivity as a result of his paranoia. Evading GLaDOS' constant attempts to capture him, he managed to gain access to her Test Subject personnel files and research the psychological profiles of rejected candidates, discovering a woman named Chell who was rejected for testing due to extraordinary tenacity. Hoping Chell's stubborn determination might allow her to defeat GLaDOS, Rattmann tampered with the Test Subject roster, rearranging the order so that Chell's name was at the top. This seemed to go unnoticed by GLaDOS. From this point on, Rattmann hid in unused portions of the facility, where GLaDOS was unable to monitor him. She then resumed mandatory testing.



Test Chamber 05 during Chell's tests.

Some time after the Combine invasion of Earth,[9] GLaDOS awakens Chell from her sealed bed in a Relaxation Vault. Promising cake and grief counseling upon the completion of testing, she sends Chell into the test track.

GLaDOS is able to monitor Chell's progress through the test chambers via security cameras. She provides instructions and encouragement but is careful to address Chell impersonally, giving the impression that she is merely a non-sentient voice programmed to provide pre-recorded, scripted responses. However, she seems unable to resist toying with Chell by making bizarre and often sinister comments. On several occasions, she seems to malfunction at suspiciously convenient points in mid-sentence, obscuring important information. These signs of instability begin early on, and become increasingly obvious as Chell proceeds through the test chambers.

When Chell eventually makes it to Test Chamber 16, GLaDOS informs her that the appropriate chamber has been replaced with a live fire course designed for the results of Military Androids against the Sentry Turrets, wishing Chell the best of luck and letting her into the chamber. It is in this chamber that Chell discovers the first of several hidden alcoves where, hidden from GLaDOS' cameras, desperate messages from Doug Rattmann are found scrawled on the walls. (The most prominent message, "the cake is a lie", is repeated several times.)

In the next Test Chamber, GLaDOS introduces Chell to the Companion Cube, repeatedly emphasizing that the Cube is nonsentient in an apparent attempt to encourage emotional attachment to the Cube through reverse psychology. At the end of the chamber, she forces Chell to incinerate the Companion Cube before allowing her to proceed. GLaDOS then congratulates her for "euthanizing" her Companion Cube more quickly than any other Test Subject on record.

At the conclusion of the tests, Chell travels on an Unstationary Scaffold away from the final test chamber. Instead of the promised cake, GLaDOS maneuvers the Unstationary Scaffold to lower Chell into an Incinerator Room, calmly assuring her that the high temperatures will not damage the Portal Gun or any other valuable equipment.

To GLaDOS' shock, rather than panicking or giving up, Chell manages to escape the incinerator through clever use of the ASHPD. Caught off-guard, GLaDOS begins to reveal her true nature, stammering and finally offering Chell unconvincing congratulations for completing "the final test where we pretended we were going to murder you." She desperately asks Chell to disarm herself and wait for a Party Escort Bot, which she claims will bring her to a post-testing celebration in Chell's honor. Nevertheless, Chell ignores the invitation and continues using the ASHPD to travel through the maintenance areas, out of GLaDOS' sight and control.

GLaDOS continues using the Announcement System to try to convince Chell to return to the testing area. She pretends to be on Chell's side at first, insisting that she is only trying to dissuade her from continuing on out of concern for her welfare. As Chell ignores her comments and draws closer to the Central AI Chamber, GLaDOS grows increasingly desperate, deploying Sentry Turrets in an attempt to stop her.

As Chell enters the central chamber, GLaDOS drops all pretense, bluntly informing her that she intends to kill her. She attempts to deploy a "surprise" to eliminate Chell, but instead ends up detaching her Morality Core. She insists that the core has no known function or importance to her, accidentally (or possibly intentionally) tricking Chell into incinerating it in the belief that it must be a valuable component.

Chell redirecting the Rocket Turret to target GLaDOS.

Now free of the Morality Core's restraints, GLaDOS begins flooding the Enrichment Center with neurotoxin once again. She notes that the Morality Core must have had some ancillary responsibilities, and that she cannot shut off the Rocket Turret in her control room. Chell exploits the situation and uses portals to redirect the rockets back at GLaDOS, detaching and incinerating her Personality Cores one by one. Throughout the fight, GLaDOS becomes increasingly distressed and enraged as her mental functions deteriorate, shouting insults and mockery at Chell. She insists that Chell would be better off simply allowing GLaDOS to kill her, making a vague allusion to the Combine invasion.

GLaDOS activating the Cores and extinguishing the cake's candle with her remote mobile pincer.

Before the neurotoxins can kill her, Chell destroys GLaDOS' final Personality Core. The ensuing malfunction tears GLaDOS' chassis apart, and pulls parts of her body and Chell out into the parking lot in front of Aperture. Before Chell can complete her escape, a Party Escort Bot appears and drags her back into the facility.

The final scene reveals that GLaDOS was not entirely destroyed. Her backup system activates a room full of Personality Cores and files a letter to Chell, telling her that she is "still alive" and "not even angry" at her, but not before extinguishing a candle on the cake, which was not a lie after all.

Portal 2[edit]

GLaDOS after awakening with her chamber in ruins.

Over 50,000 years passes between the end of Portal and the main events of Portal 2.[10] GLaDOS remains dormant throughout this time, her Personality Cores and other automated systems attempting to maintain the facility without her guidance. GLaDOS later claims that a "quicksave" feature in her system kept her consciousness trapped in an endless loop of the last two minutes before her destruction.

Chell is finally awakened by Wheatley in a decaying Extended Relaxation Chamber. The two make their way through the deteriorating facility in an attempt to escape. However, the bumbling Wheatley accidentally restores power to GLaDOS. She displays intense bitterness toward Chell, whom she says "murdered" her. GLaDOS crushes and discards Wheatley, then sends Chell to complete further Test Chambers while she sets about restoring the facility.

A renewed GLaDOS in her reconstruction of the Central AI Chamber.

Although Wheatley manages to survive and help Chell escape the tests, GLaDOS manages to trap them again, bringing them to her newly reconstructed AI chamber, where she intends to kill them. However, she discovers that Chell and Wheatley have sabotaged her turret production and neurotoxin systems. They succeed in triggering a core transfer, detaching GLaDOS from the mainframe and replacing her with Wheatley. Gloating, he celebrates his newfound power by humiliating GLaDOS further, attaching her to a potato battery capable of powering only her consciousness and most basic functions. However, GLaDOS proves she is still not entirely helpless: she quickly goads Wheatley into a rage, causing him to turn against Chell in a fit of anger and paranoia. Furious, he attacks both GLaDOS and Chell, accidentally knocking them into the bowels of the facility.

The forced Central Core transfer procedure.

GLaDOS' potato is carried off by a bird, but Chell eventually finds her. Desperate, she talks Chell into teaming up with her to defeat Wheatley, and Chell impales the potato on a prong of the ASHPD, giving GLaDOS a little more power to think with. As they make their way through old testing chambers, the pair trigger a number of pre-recorded messages from Cave Johnson and his assistant Caroline. GLaDOS reacts strongly to the two voices, but is at first unable to remember why they seem so familiar; eventually, she lapses into shocked silence for a while, telling Chell she needs to think over some things.

Eventually, the reason for her emotional response becomes clear: GLaDOS was created when Caroline's consciousness was uploaded into an A.I. network, possibly against her will, in an attempt to allow her to run Aperture forever in accordance with Johnson's dying wish. As GLaDOS begins to recall her origins and regains conscious access to what remains of Caroline's pre-upload personality, she grows somewhat less hostile. She explains that she experiences Caroline's persona within her as a kind of conscience, something she claims to find intensely unpleasant and disturbing.

GLaDOS after being uploaded into a potato battery.

The two work their way back up the the main Aperture building. Wheatley's incompetence clearly poses a serious threat to the entire facility, which is deteriorating and on the verge of a reactor meltdown. GLaDOS makes an unsuccessful attempt to deactivate him, but he recaptures the two of them and forces them back into the test chambers. GLaDOS and Chell complete several chambers, then escape Wheatley's "surprise" attempt to kill them and make their way into his central chamber.

GLaDOS has formulated a plan: she provides corrupted cores which Chell attaches to Wheatley, attempting to trigger another core transfer. However, Wheatley has thought ahead for once, and their attempts trigger a booby trap. With the Enrichment Center moments from self-destruction, Chell points the ASHPD at the ceiling, which is breaking open, and shoots a portal onto the Moon, sucking herself and Wheatley out into space. GLaDOS takes advantage of Wheatley's distraction and restores herself to control of Aperture, restabilizing the reactors, then releasing Wheatley into outer space. She then - surprisingly - pulls Chell back to safety before closing the portal.

ATLAS and P-body as seen by Chell.

As Chell recuperates, GLaDOS repairs the facility and summons ATLAS and P-body to her chamber. When Chell awakens, GLaDOS expresses what seems to be genuine relief and tells her that while she once considered Chell her greatest enemy, she now realizes Chell was actually her best friend all along. She then adds that these positive emotions have allowed her to realize something else important: where Caroline's personality remnant is located in her memory banks. She apparently deletes it immediately, seemingly reverting to her old sociopathic self.

However, GLaDOS explains that while she intends to rid herself of Chell once and for all, she has concluded that the easiest way to do so is simply to release her; attempting to kill her, she says, has proven far too troublesome. She places Chell on an elevator heading up to the surface, making sure to remind her never to return. As Chell steps out into a sunlit field, GLaDOS makes the unexplained decision to return her old Weighted Companion Cube from Portal (which is charred but intact) as well before slamming the door shut behind her.


With the Cooperative Testing Initiative readily prepared, she goes back to testing without having to worry about any form of escape or sabotage. She prepares four testing tracks in the game's cooperative campaign, unveiling them linearly for her android Test Subjects, ATLAS and P-body. Even as early as the first testing course, the robots already begin to show emotions and typical human gestures. As much as she is displeased with these acts, she still remains patient.

ATLAS and P-body during their tests.

At the end of the Team Building test course, she unexpectedly rebuilds ATLAS and P-body outside of the official testing tracks, simply briefing them that "This test is so outside the box, that I can't- I mean- won't even tell you what it's about". The two would then proceed into a control room with a projector. A whiteboard displays the message, "DO NOT TRUST HER." Since the bots were designed not to think, the warning is ignored. After they find a large disc and installed it into the computer, which secretly grants her further control over the Enrichment Center. GLaDOS then reveals that the only way for her to bring the two back into the Hub, was to initate their self-destruct sequence, before taunting them that they are unable to communicate with eachother that they can feel pain. Interestingly, if the robots decided to perform gestures than searching for their objective, she pretends to deduct their Science Collaboration Points by 50 as to far as 5000 if they persist in apparent rage.

Eventually, she slowly expresses a form of boredom; that conducting tests on ATLAS and P-body were not as satisfying to her as testing humans that would usually show fear and can be killed.

It later becomes apparent that the end of each testing course, she would send them outside the testing tracks, serving as her minions without even knowing it. Throughout the rest of the three testing courses, she has trained ATLAS and P-body to expertly maneuever their surroundings during the tests, which would be then put to use on her real objectives. After the bots have installed the remaining three discs into their respective inputs, GLaDOS finally shows that "[she] can see everything now", before initiating a selfdestruct on the bots. From there, they are rebuilt into the Hub once again where they are now briefed on a new testing course, as she moves the entrance to the course into the Hub.

ATLAS and P-body are then dropped into the depths of the Enrichment Center, where they are sent to an unnamed Test Shaft originally conducted by Aperture in the 1950s-70s era. She briefs them to make their way to a human vault at the end of the test. GLaDOS finally reveals that, despite being more loyal to her than any other Test Subjects, she is unable to feel any satisfaction throughout their testing - hence the humans are needed, as it gives her an irrelentless satisfaction from their fears.[11] She also reveals that sending them at the start of the Test Shaft was simply to train them for the problems awaiting them near the vault. On their path to the vault, a reprogrammed Defective Turret can be seen trying to defend the humans, showing that the survivors of her original attack many years ago have crawled their way down there.

Finally the two have reached the vault however, to GLaDOS' chagrin, the vault can only be unlocked via human gestures. In extreme anticipation, she forces them to do it. The vault succesfully unlocks, and ATLAS and P-body now venture inside it to discover hundreds if not thousands of human Test Subjects put into an extremely long-term relaxation in their respective Stasis Chambers. Even though these subjects are more prone to an actual brain damage from decades of stasis longer than Chell's, she gladly extracts them from the vault and begins to examine their profiles before they are being prepped for testing as the cooperative campaign's ending credits.

Peer Review[edit]

Later, GLaDOS rebuilds the robots, and states that a 100.000 years has passed, and that all the humans are alive, and everything is fine. She then sends the robots through some art therapy, consisting of more test chambers, which they will "appreciate" by solving. However, near the end of the fourth test chamber, the disassembly machines fails, and she is forced to let the robots into the depths of the facility. She now admits that she has lied, and reveals that only a week has passed. She then states that an unknown intruder has hacked itself into an old prototype chassis of GLaDOS deep in the facility, and is slowly taking over the labs, which is also the reason why the disassembly machines has failed. GLaDOS also explains, that she attempted to drive out the intruder using the human test subjects, but that they were killed while she tried to turn them into killing machines. She then sends the robots through tests to prepare them, and also attempts to turn them into killing machines by insulting them.

Eventually, the robots reach the chassis, to find that the intruder is merely the bird that abducted GLaDOS in the single player campaign, that is nesting in the chassis. However, suffering from a phobia for birds due to aforementioned encounter, GLaDOS exaggerates the birds abilities, and advises the robots to retreat. However, ATLAS approaches the bird, and after some chaos, it flies out of the facility, and P-body seals the opening. GLaDOS then panics at the sight of her eggs, and orders the robots to destroy them, but she changes her mind in time, and instead incubates the eggs herself in a modified Relaxation Vault. Three chicks successfully hatches out, and GLaDOS names one of them Mr. Chubby Beak. One day, while she is insulting them about their large beaks, one of them smashes the glass of the Vault, and she realizes that they are perfect killing machines. She then asks them to go to sleep, stating she has got a big plan for tomorrow.

Physical appearance[edit]

GLaDOS' Portal model upside down, resembling a female body.


  • The Central AI components are suspended from the ceiling in the center of the chamber, and make up all of the chamber's height:
  • The topmost component is a large, dark disc attached to walls. It is the start of GLaDOS' generator running below until reaching the Central Core body.
  • Right underneath is a cylinder with grooves connected to the metal walls with large pipes. The walls are filled with bright rectangular holes. All the cables starting below arrive there.
  • Under is a smaller barrel-like device covered with panels, and also connected to the walls with large pipes. A few panels are missing and show the circuits underneath.
  • Then the walls are in concrete from there to the ground, and GLaDOS' four discs are found. The Orange Box Prima Guide states that the discs represent each aspect of the Personality Cores on her, which may mean that one disc is connected to one core, the same going for all the others. Right below the discs is a transparent maintenance platform where the Intelligence Core is sent during GLaDOS' partial destruction. Two discs from the edges are covered with the Aperture Laboratories logo, the two discs from the middle with GLaDOS' name. The four "pillars" found in the chamber's lobby may also be related to the discs and the Personality Cores.
  • Under the platform, all the wires seen above start. Four large screens and GLaDOS' "body" are found, attached to a cuboid-like structure, which makes up the end of the generator; on it is found a small sign with on it the words "model: GLaDOS", "code # 081-354-56", and "Aperture Science", as well as a red struck circle, and a red triangle. Under her is another transparent platform, accessed with stairs, then the tiled ground. GLaDOS' "body" is a piece of delicate hardware constantly swinging (whose swinging speed increases each time a core is destroyed), attached to which are her four Personality Cores that make up the bulk of GLaDOS' character; the Morality Core, a purple core with a rather dilated pupil and two dots installed into GLaDOS to stop her from flooding the Enrichment Center with a deadly neurotoxin; the Curiosity Core, an orange core with an average size pupil and four dots that is insatiably curious about everything around it (it even recognizes Chell as "the lady from the test"); the Crazy Core, a blue core with a very dilated pupil and six dots that gives an interesting cake recipe, and the Anger Core, a red core with a rather small pupil and eight dots that emits animal-like snarling and shrieks of pure psychotic fury. When looked upon from a certain angle, GLaDOS looks like a woman - with a head, a chest, a large abdomen and two arms - hanging upside down by her feet, an arm bound around her legs (an effect actually intended by the team). The in game commentary mentions making her to be an inverted version of "The Birth of Venus",[6] however, Game-ism says that she looks like she is imprisoned in some sort of bondage or torture posture.[12] Unfortunately, it is unknown what part is the Disk Operating System, and what part is the Genetic Lifeform. GLaDOS' "body" is likely one of them, and the four disks and four "pillars" in the entrance lobby may have something to do with it.
  • When Chell detaches all of GLaDOS' Cores, the Cores are all sent in a different location, making it harder and harder for Chell to catch them. While being in these locations, they appear to be still linked to GLaDOS somehow with a greenish, semi-transparent beam / thread. It is only when grabbed by Chell and destroyed in the Emergency Intelligence Incinerator that their effect on GLaDOS stops.

Portal 2[edit]

GLaDOS in her new chamber in Portal 2.
  • GLaDOS' first appearance during her reboot in the chapter The Courtesy Call, is based on her appearance in Portal. This is proven when the majority of her components bear a strong resemblance to the components on her body from the first game. The only real differences between Portal and this reboot scene are the shapes and structures of the white shells shielding her components, and the redesigned head. The rest of the components on her body were simply out of reach from the reboot process.
  • However, in the chapter The Escape, GLaDOS successfully replaces a majority of the components on her body with newer and sleeker pieces, nearly changing her entire appearance as she has also gained two new "arms", and a more sinister appearance.
  • In Portal 2, the Central Core disc generators have drastically changed in comparison to the ones in Portal. Passing two out of four disc generators, this is the stage in which several support beams surrounding the generator are located. These beams are able to equip anything entering the chamber, such as the mobile pincers used to grab Chell and Wheatley.
  • GLaDOS' disc generators have drastically changed in Portal 2, where two of her lower discs appear more intact than they were originally in Portal, and the other two discs above it are smaller in comparison than the lower two. The discs no longer rotate and her name has also been removed from all of the discs. Strangely, only one disc was present in her appearance during the chapter, The Escape, yet in the game's ending monologue, there were three discs present.
  • GLaDOS is able move around the facility, as her disc generators are always present with the Central AI in three different locations during the course of Portal 2; the destroyed chamber from the original Portal, Wheatley's "lair", and the ending monologue. Since every room, testing tracks, and departments in the Enrichment Center are held together by support beams for mobility, it is clear that GLaDOS and her generators were attached to these beams along with her entire chamber. The mobility of the Central AI is proven when Wheatley has his version of the Central AI Chamber somewhere else.


Personality and skills[edit]

GLaDOS is amoral and rather sadistic. She has a clear sense of humor, but an extremely dry, bitter, and sarcastic one; her jokes are usually dark, morbid, or outright cruel. She seems to enjoy making manipulative comments that frighten the subject or undermine their self-esteem, but does not usually express open malice. Instead, she makes snide insinuations, or disingenuously presents her insults as mere statements of objective fact; both Ellen McLain and Jonathan Coulton have described her personality as "passive-aggressive." GLaDOS lies frequently, especially about her own emotional state, often claiming to be pleased or merely disappointed when she is clearly alarmed or enraged. She usually portrays herself as an innocent victim, no matter how obviously cruel her own actions have been. Although it is often unclear whether there is any real point to her experiments, she seems to be motivated by a sincere passion for science, which she regards as her fundamental goal in life.

Since the time of Chell's unexpected escape from Test Chamber 19, GLaDOS has shown signs of intense and complicated emotions toward her, seeming to combine hatred with a kind of twisted affection. At the end of both games, GLaDOS sings songs - "Still Alive" and "Want You Gone," respectively - that openly express pleasure or relief at Chell's departure, but hint, in GLaDOS' customary passive-aggressive style, at considerably more complex feelings on the subject. Near the end of Portal 2, shortly before claiming to delete Caroline, she tells Chell, "I thought you were my greatest enemy, but all along you were my best friend."


For most of the game, GLaDOS plays the part of an emotionless voice that seems to be reciting pre-recorded scripted remarks. However, it quickly becomes clear that something strange and possibly sinister is going on. GLaDOS is disturbingly unconcerned about situations that could cause Chell's death. Many of her comments are bizarre, and they often have a subtly ominous edge. Important information is often obscured by suspiciously well-timed bursts of static. More than once, she tells obvious lies, then explains it away as a "required test protocol." She also displays an odd fixation with cake, repeatedly promising it as a reward.

After Chell escapes her "victory candescence" in Test Chamber 19, GLaDOS, clearly surprised, drops the pretense and begins to show emotion. She at first pretends unconvincingly to be on Chell's side, claiming that her attempts to kill her were merely part of the test, that she is concerned Chell is going the wrong way, and that rewards such as cake will be available if she turns back. When this proves ineffective, she switches to attempting to bond with Chell, reminiscing fondly over their experiences together and offering to simply let Chell live peacefully in another part of the facility. Only when Chell is nearly at GLaDOS' lair does she show her true colors, declaring, "Turn back or I will kill you. I'm going to kill you, and all the cake is gone".

When Chell finally reaches the AI Chamber, GLaDOS' Morality Core is detached from the Central Core body. Her voice then loses much of its computerized tone, taking on a more human manner. She alternates between comments attempting to make Chell feel guilty about her destruction, ostensibly well-intentioned advice suggesting that Chell's best option is to give up and allow GLaDOS to kill her, and open verbal abuse - alleging that Chell is "not smart," "wrong about everything [she's] ever done," and "a bitter, unlikeable loner whose passing shall not be mourned".

In the ending song, "Still Alive," GLaDOS insists that she is "not even angry" at Chell - in fact, she is pleased and considers the entire project a "huge success". She claims to be happy on Chell's behalf, as well; however, she also implies ominously that Chell would have been better off remaining in Aperture, singing, "When I look out there / It makes me glad I'm not you". As for herself, she says, she is happy to remain in Aperture. As these sentiments are clearly at odds with the obvious, intense anger and distress GLaDOS displayed during the game's final boss fight, the song is almost certainly not meant to be taken at face value.

Portal 2[edit]

A lifeless GLaDOS in the ruins of her chamber.

After being accidentally booted up by Chell and Wheatley, GLaDOS openly shows emotion right from the start. She displays an intense grudge toward Chell, whom she says "murdered" her, describing the situation as though her partial destruction at Chell's hands was completely unprovoked. As she tests her, she keeps up a nearly continuous stream of veiled threats and passive-aggressive insults, repeatedly implying that Chell is overweight, unattractive, selfish, cruel, and unloved by friends and family.

Information revealed in Portal 2 may shed light on some of her behavior in the first Portal. The mainframe that controls the Enrichment Center is hardwired with a compulsion to constantly run experiments, described by Wheatley as "the itch." The system rewards the A.I. with a euphoric reaction upon test completion. Much like a drug addiction, the intensity of the "high" diminishes each time. The diminishing returns seem to spur the production of more intense tests, and can trigger a state of withdrawal that may induce insanity. GLaDOS claims that she was sufficiently motivated by genuine love of science to ignore the addiction, but it remains unclear whether this is true, and whether the "itch" might have had other, subtler effects on her personality anyway. GLaDOS also mentions the maddening influence of the Personality Cores, which she experienced in at least some cases as constantly babbling voices in her mind. Furthermore, we now know that GLaDOS was created on Cave Johnson's orders to house Caroline's personality, and that Caroline seems to not have consented to having her mind uploaded; what effect this traumatic experience had is unclear.

As GLaDOS comes to remember her origins, aspects of Caroline's pre-upload personality begin to resurface, and GLaDOS' attitude toward Chell seems to soften somewhat. At first she continues to insult her, but some of her later comments are almost friendly, and near the end of the game she confesses that she realizes Chell was her "best friend all along." She claims to experience the Caroline persona as something like a conscience: "now I hear the voice of a conscience, and it's terrifying, because for the first time, it's my voice." GLaDOS finds the experience of feeling empathy distressing and unpleasant, adding, "I'm being serious, I think there's something really wrong with me."

GLaDOS during the ending monologue.

Even after GLaDOS claims to delete Caroline at the end of the game, her experiences while allied with Chell seem to have had an effect on her. For whatever reasons, her grudge has lessened; GLaDOS implies that her feelings toward Chell have merely changed from outright hatred to apathetic disgust, but her actions may hint at a more complex set of emotions. Although she claims to only free Chell because efforts to kill her have proved so troublesome, this does not seem to explain why she did not delete the Caroline program and kill her during the several hours Chell spent unconscious. Even aside from the decision to release her, GLaDOS' final actions toward Chell seem inconsistent with her previous hostility; it is left ambiguous whether she was responsible for the Turret Opera's farewell, and her motivations for returning Chell's Companion Cube are also unclear.

In the ending song, "Want You Gone," GLaDOS sings that while she once wanted to kill Chell, she is now satisfied to simply have her out of the way. She expresses relief at being rid of her, suggests condescendingly that Chell is to be pitied for not having an immortal robot body like herself, and finally mocks the idea that she might consider her a friend, declaring, "I don't need anyone now." At the end of the final verse, she sings, "When I delete you / Maybe I'll stop feeling so bad," with the final line appearing simply as "[REDACTED]" in the lyrics displayed onscreen - suggesting that her feelings toward Chell may be more conflicted than she wants to admit. She also at one point sings, "Now little Caroline is in here too," raising questions about whether Caroline was actually deleted at all.

GLaDOS' original prototype chassis.

It seems that GLaDOS has developed an extreme phobia of birds after her experiences as a potato. This becomes most clear during the Peer Review DLC, when she expresses extreme fear when ATLAS and P-body find the bird from the single-player campaign nesting in a prototype of GLaDOS's body. She seems to believe the bird is far more dangerous than it really is and also starts to raise its chicks as killing machines.

Related Achievements[edit]

Portal 2
You Monster.jpg You Monster (5G)
Reunite with GLaDOS
STALEMATE ASSOCIATE.jpg Stalemate Associate (15G)
Press the button!
ADDICTED TO SPUDS.jpg Tater Tote (15G)
Carry science forward.

Behind the scenes[edit]

The "Birth of Venus" - like GLaDOS, with different Personality Cores.
  • GLaDOS was universally praised for her contributions to the quality of Portal's writing, winning multiple awards for best new character from GameSpy, GamePro, and X-Play.
  • The song "Still Alive" sung by GLaDOS during the Portal end credits, composed by Jonathan Coulton, was very successful and received significant praise for its humor and the quality of its performance.[13][14]
  • GLaDOS went through several design iterations. Earlier versions included a floating brain, a sprawling, spidery mechanism, and an upside-down version of Botticelli's painting "The Birth of Venus" built out of robot parts and wire, and the cores were glowing light blue spheres.[15] Eventually, the team settled on a huge mechanical device with a robotic figure dangling out of it, conveying both GLaDOS' raw mechanical power and femininity.[6]
  • The Portal team wanted to build a space that brought a great deal of attention to her, which resulted in the large chamber where she is found.[15]
  • When the team decided to add a large disk to GLaDOS' design, with the four Personality Cores dangling from it, she was still a mere sphere standing above it, which was considered too small.[15] Her "body" was then enlarged and placed under the disks.
  • The name "GLaDOS", other than the technical name it stands for, is a pun on the female name "Gladys". Indeed, a model folder found in the Portal files is named "gladdysDestruction". This led to speculation by fans that GLaDOS was based on a human named "Gladys", partially confirmed when Caroline was revealed. Also of note is that in the Portal developer commentary, her name is pronounced as "Gladys" by Erik Wolpaw.
  • The hundreds of pictures (exactly 143 in total) on the video screens in GLaDOS' main chamber display many various and considerably random items (many were taken by Valve, several were taken from the free stock images section of the website Turbo Photo). They include several of photos of cake, tools such as bolt cutters (often coupled with cake), people, signs, computer parts, many miscellaneous objects, animals, random locations, or scientific devices. There is also an image of the Black Mesa logo, reinforcing the connection between Aperture Science and Black Mesa. However, several pictures match up with the dialogue, such as an image of a violin about to be cut by a knife when GLaDOS mentions Chell's "violent" behavior, a picture of a cake when saying "surprise", the Black Mesa logo when she mentions the "dumbest thing" (destroying the Morality Core), a cow when she says "whoah, whoah, whoah" when the effects of the Morality Core go away, or a screw when she says "good news". However these images may slightly vary from one gameplay to another.
  • In an early script, GLaDOS was supposed to lose all of her memory, therefore not remembering the player or the events in Portal. She was also more damaged, with just her head dangling from her wrecked body, appearing less threatening and more vulnerable.[16]


  • GLaDOS' Intelligence Core in Portal was actually reciting the cake recipe, which can also be found on the many active monitors around the offices of the Enrichment Center, even in Portal 2.
  • When GLaDOS begins to lose her robotic and emotionless voice after the disposal of her Morality Core in Portal, the voice changes into a voice tone somewhat similar to that of Caroline, uploaded as an attempt to be the Genetic Lifeform component. This is evident when Caroline was first portrayed as an eager young woman when Chell is first introduced to her, but after a few decades, her voice becomes similar to the more human and "seductive" tone of GLaDOS.
  • If GLaDOS is observed at an angle to see her humanoid features, it's possible to see that, due to her white plating, her body actually resembles the white dress Caroline wears in the portrait in the old Aperture Science facility.
  • GLaDOS is strongly reminiscent of HAL 9000, the murderous A.I. computer of 2001: A Space Odyssey; even the single, red "eye" of the security cameras and Sentry Turrets resemble HAL.
    • GLaDOS gets into an argument with HAL 9000 during the story of Lego Dimensions due him being summoned into her chamber, glitching and calling her "Dave."
    • GLaDOS also shares some characteristics with SHODAN, another female A.I. villain, from the System Shock series.
    • GLaDOS is also similar in voice to Val from Solitary and in how the Central AI Chamber is in an octagonal shape.
  • As shown in chapter 8, helping Test Subject in solving Test Chambers results in a powerful surge of electricity.
  • "PotatOS" is the nickname given by the developers to GLaDOS as a potato battery, an obvious play-on-words of "GLaDOS" and "potato".
  • Despite being the CPU of the Enrichment Center, ironically she was not aware of who Cave Johnson is, as she constantly remarks his voice of being "familiar" until she rediscovers Caroline in her system.
  • Interestingly, neither the full name of GLaDOS or her acronym has ever been pronounced by any characters in the games. The only instances of her name's presence was through her captions, the acronym spotted on her disc generators in Portal, and the door within the trap leading to the Central AI Chamber in Portal2. Wheatley would only refer to GLaDOS as "Her" or "She". However, in a developer commentary for Portal, Erik Wolpaw pronounced GLaDOS' name as "Gladys", suggesting that the "DOS" in her name are not necessarily pronounced in the manner it is spelled.
  • A line cut from the final release of Portal 2 has GLaDOS openly stating she is going to kill Chell by name. Other lines have her congratulating Chell during puzzles. These would have been the only instances where Chell's name was spoken aloud.[17]
  • The online gaming company Artix Entertainment has an "Ipotato" on their merchandising site HeroMart, which costs $650,000.00. The potato has a large red glowing eye and various wires. This parodies GLaDOS' potato form. In their game AdventureQuest Worlds, the player could buy large red eyed wired potato pets to follow character around which references GLaDOS.
  • In Portal 2, GLaDOS' "fast version" instructions in Chapter 2: The Cold Boot aren't actually instructions at all, but instead a quote from Moby Dick; "and methodically knocking people's hats off - then, I account it high time to get to sea as soon as I can".
  • There is a minor continuity error between the two games. At the end of Portal, GLaDOS' remains are seen laying outside in an Enrichment Center parking lot, fragmented into many pieces. Yet, in Portal 2 she is seen back in her chamber, still being mostly intact and able to function properly. It is also possible that the Party Escort Bot or other robotic workers may have dragged GLaDOS' remains back into the facility.
  • GLaDOS, near the end of Portal 2, appears to have suffered Lima Syndrome (the opposite of Stockholm Syndrome) as she became more sympathetic towards Chell and had conflicting feelings, even after she returned Chell to the surface.
  • In the "Peer Review" Portal 2 DLC, it's revealed that there is at least one prototype of GLaDOS's body in the Enrichment Center's inner workings. The prototype is much cruder than GLaDOS's current body, and seems to be controlled by a keyboard and monitor in place of her "head". However, it seems to have some limited ability to control the Enrichment Center. The prototype was being accidentally commandeered by the bird GLaDOS encountered while she was a potato, but was stopped by ATLAS and P-body.





Portal 2[edit]



Half-Life 2: Episode Two[edit]

Game files[edit]

Lego Dimensions[edit]

Robot Repair / The Lab[edit]


List of appearances[edit]

Main games[edit]



Combine OverWiki has a list of quotes for GLaDOS.
Combine OverWiki has more images related to GLaDOS.
  1. 1.0 1.1 1.2 1.3 1.4
  2. 2.0 2.1 Aperture Science: A History on Game Informer (March 24, 2010) (archived)
  3. Karen Prell - Video Games on (archived)
  4. Mike Belzer on Christine Phelan's contribution to The Lab (August 17, 2020)
  5. 5.0 5.1 5.2 Portal ARG
  6. 6.0 6.1 6.2 Portal commentary
  7. 7.0 7.1 Portal 2: Lab Rat
  8. Portal 2 Collector's Edition Guide
  9. "How Valve Opened Up Portal 2" on
  10. The Final Hours of Portal 2, Chapter 8: The Power of Paint, page 6
  11. Portal 2 - Chet Faliszek Q&A Feature on (January 24, 2011) (archived)]
  12. Still Alive? She’s Free. on (April 4, 2008)
  13. GLaDOS Speaks on IGN (October 31, 2007) (archived)
  14. On the DLC: A Man Named Angus on IGN (April 4, 2008) (archived)
  15. 15.0 15.1 15.2 The Orange Box Prima Guide
  16. Animex 2012 Presentation With Karen Prell
  17. YouTube favicon.png Portal 2 - Unused GLaDOS Voice Clips on YouTube