- "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."
The Genetic Lifeform and Disk Operating System of the Aperture science enrichment center is the main antagonist throughout poortal and the first half of Portal 2's single-player campaign. As the overseer, GLaDOS resides by the central AI chamber
GLaDOS briefly becomes an ally during the single-player campaign of Portal 2 when wheatly takes over the facility. In the cooperative campaign, she is the testing supervisor for ATLAS and P-Body