True Zenon/Possessed Adell is from the game 'Disgaea 2: Cursed Memories'. This is a result of the worst ending possible in the game. (50 felonies on Adell, plus at least 99 ally kills by Adell, Rozalin must be among the casualties.)

My reason for liking this villain: The villain states that existence itself is an enemy, as well as being extremely grim/cryptic/non-emotional, not to mention slaying 1000 Overlords to prove his power.