GLaDOS (Genetic Lifeform and Disk Operating System) is a fictional character in the 2007 Valve Software video game Portal. She was created by Erik Wolpaw and Kim Swift. She is an artificially intelligent computer system in charge of operating the Aperture Science research facility, which is the setting of Portal. While initially appearing as a voice to guide and aid the player, her words and actions become increasingly malicious, making multiple attempts to kill the player-character. She eventually is revealed to be insane, having killed the scientists who ran Aperture previously with a deadly neurotoxin before they could install her morality core. She is set to appear in the sequel, Portal 2, taking place hundreds of years after the player-character defeats GLaDOS and being placed back in the chamber.
For much of Portal, GLaDOS is a voice which acts as a narrator and guide for players. Her voice is robotic, but distinctly female. Her personality has been described as passive-aggressive, witty, and sinister. She has a number of system personality cores installed into her, partly in order to prevent her from killing anyone. Eventually, once the player encounters her, she is revealed to be a complex computer, with robotic parts hanging from a larger device. The device displays rapidly changing images on a series of monitors, an example of the images being pieces of cake. Upon removing the first personality core, the morality core, GLaDOS' voice becomes less robotic and more sensual. It is revealed in the later portions of the game that she was originally conceived as a means of competing with their competitors, Black Mesa. She was created as a device to de-ice fuel lines. However, she also has a fully-functional disk operating system. The AI of GLaDOS is installed as the Enrichment Center's central control computer, mounted in a large, sealed chamber alongside control consoles and an incinerator.