GLaDOS (Genetic Lifeform and Disk Operating System) is an artificial intelligence created by Aperture Science. She is the main antagonist throughout Portal and the first half of Portal 2's single-player campaign. As the overseer and highest of authorities of the Enrichment Center, GLaDOS resides in the Central AI Chamber. GLaDOS briefly becomes an ally to Chell during the second half of the singleplayer campaign of Portal 2 after Wheatley takes over the facility. In the cooperative campaign, she is the testing supervisor for ATLAS and P-body.