Aperture Science

GLaDOS (Genetic Lifeform and Disk Operating System pronounced "Glej-doss") is the the Guide at Aperture Science. She is issuing instruction in the use of the Portal Gun and offering oblique and occasionally sinister advice and warnings. Her smooth female voice, issued through a PA system which pervades the whole of Aperture Science Enrichment Center, is the only outward face of the organization the player is ever aware of, or allowed to be aware of. It is not obvious who or what GLaDOS is, and what her actual role is at Aperture.

GLaDOS represents Aperture Science, and guides the player from their chamber into and through the test course. It swiftly becomes obvious that despite her polite and equable tones GLaDOS is neither particularly bothered by what happens to the player, nor entirely rational. She frequently lies about such concerns as the deadliness of acid pits, and also has a fixation with Cake, which she insists will be served after the test is completed. She presents this and the bewildering and dangerous tasks the player is forced to perform as common procedure at Aperture. GLaDOS is also prone to vocal malfunction, often blotting out important pieces of information in bursts of static.

Don't let the above information be a distraction from registering to Aperture!
Observe that the cake is NOT a lie - the cake will be served after completing the tests. Remember: You will be baked, and then there will be cake!