[Death by Mirrors]

I don't think I have a least favorite killer, but personally I've always thought the trinity killer in the Dexter series was pretty overrated. He comes across so pathetic and his story is full of plot holes. Let alone the fact this guy is of way too disturbed a mind to display such a high level of functionality when he's not killing.

And I can't look at Darth Vader the same way again either after seeing his "fall for the dark side" was some sort of moody teenage rebellion.