In a contest about video game villains, does Vader's game appearances even compare to GLaDOS's? He ended up winning 60-40 due to his rich movie history, not because of video games. That's a travesty on-par (if not worse) with how Master Chief and Sephiroth were screwed in past contests.
You support the idea of adding other fictional characters though, so we're not gonna see eye-to-eye on this.
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http://img812.imageshack.us/img812/3492/eponaharr.jpg
Nominate E P O N A.