Main Operation System for Aperture Science, testing with 2 robots, but used to test with humans. One of them was a enemy then ally of Glados, Glados however doesn't like humans too much. Glados does not know what happened on the surface, as Aperture Science is underground. She also has the ability to deploy a deadly gas called Neurotoxin, along with deadly sentries, that both talk and sing, sometimes sympathizing for people, which also being capable of receiving pain, then rocket sentries.