"I hate these little moments of quiet before the crying starts." - GLaDOS
GLaDOS (Genetic Lifeform and Disk Operating System) is the antagonist of Portal. She is a supporting character in Portal 2. She is the dealer in Poker Night 2.
Originally found managing the Aperture Science test facilities, GLaDOS made her debut in Portal. She later returned in Portal 2.
GLaDOS is one of the gaming world’s favorite characters (in spite of her passive-aggressive tendencies and desire to watch you die).
The Team Fortress 2 unlock for GLaDOS is Chell's Long Fall Boots. Once unlocked, they can be used by The Scout.
(Note: despite their purpose in the Portal series, Scouts equipted with Long Fall Loafers will still take fall damage.)
The Borderlands 2 unlock for GLaDOS is a skin based on the Aperture Science turrets. Once unlocked, it can be used by Zer0.
Using all of the Portal items changes the Inventory into an Aperture Science (current not retro) setting. Some points of interest are a Portal Gun mounted above the bar and what appears to be a Vital Apparatus Vent dropping objects into a mirrored version of itself, acting more like a pipe. Among these objects are Weighted Storage Cubes, Turrets, and even a large version of Tycho's 20-sided die. There are two vertical hard-light bridges on the stage around the Apparatus Vent. Claptrap is reskinned as an Aperture Science Turret, and players that are knocked out are forcibly ejected from the table via portal. Winning the tournament causes GLaDOS to belittle the player and seemingly threaten to kill them before passing off her threats as a joke and triggering a laser light show using several turrets.