GLaDOS is a fictional character from the video game series Portal. The character was created by Erik Wolpaw and Kim Swift and voiced by Ellen McLain. GLaDOS is depicted in the series as an artificially superintelligent computer system responsible for testing and maintenance in the Aperture Science Computer-Aided Enrichment Center in all titles. While GLaDOS initially appears in the first game to simply be a voice that guides the player, her words and actions become increasingly malicious as she makes her intentions clear. The second game, as well as the Valve-created comic Lab Rat, reveals that she was mistreated by the scientists and used a neurotoxin to kill the scientists in the laboratory before the events of the first Portal. She is apparently destroyed at the end of the first game but returns in the sequel, in which she is supplanted by her former intelligence dampener and temporarily stuck on a potato battery, while her past as the human Caroline is also explored.

Portal is a series of first-person puzzle-platform video games developed by Valve. Set in the Half-Life universe, the two main games in the series, Portal (2007) and Portal 2 (2011), center on a woman, Chell, forced to undergo a series of tests within the Aperture Science Enrichment Center by a malicious artificial intelligence, GLaDOS, that controls the facility. Most of the tests involve using the "Aperture Science Handheld Portal Device" – nicknamed the portal gun – that creates a human-sized wormhole-like connection between two flat surfaces. The player-character or objects in the game world may move through portals while conserving their momentum. This allows complex "flinging" maneuvers to be used to cross wide gaps or perform other feats to reach the exit for each test chamber. A number of other mechanics, such as lasers, light bridges, high energy pellets, buttons, cubes, tractor funnels and turrets, exist to aid or hinder the player's goal to reach the exit.