Top 98 Greatest Video Game Villains of All Time

4-GLaDOS (Portal 1 and 2)

Though initially she is a voice that guides the player, GLaDOS seems like a sweet and unassuming AI. But as the player progresses she becomes quite unstable and her actions become increasingly hateful. The player then discovers that it was GLaDOS who used a neurotoxin to kill the scientists in the lab. Her actions are of a narcissistic, passive-aggressive nature, but her witty lines make her a great villain.