Warren Mears

Warning: Wikipedia contains spoilers.

Warren was introduced in the Season Five episode, I Was Made To Love You, as a lonely young man who built a robotic woman for company (and, indeed, sex). During the course of the show, Warren progressed from such relatively innocuous beginnings to an all-out evil, misogynistic killer. In Season Six, he was the leader of the Troika, the crime gang trying to take over Sunnydale through technology and magic.

His plans, of course, were thwarted by Buffy, propelling him into a murderous fury in the episode Seeing Red where he shot Buffy and Tara, killing the latter, and leading Willow to take bloody revenge in the next episode, Villains, in which she tortured and killed him.

Some fans feel that the character of Warren was written inconsistently, with his misogynism and murderous nature being added suddenly in the episode Dead Things for the purpose of setting up the destructive climax of Season Six. Others say his descent into evil was gradual and well-crafted.