GLaDOS (Genetic Lifeform and Disk Operating System) is a fictional artificially intelligent computer system appearing in the video games Portal and Portal 2. The character was created by Erik Wolpaw and Kim Swift and voiced by Ellen McLain. GLaDOS is responsible for testing and maintenance in the Aperture Science research facility in both 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 game reveals that she is corrupted and used a neurotoxin to kill the scientists in the laboratory before the events of Portal. She is ostensibly destroyed at the end of the first game but returns in the sequel, in which she is comically supplanted and temporarily stuck on a potato battery.