Obsessed

Villains who obsess over something other than power (because obsession with power counts as Power Hungry) or money (for it counts as greed), and they have a fixation that they take extreme interest in what they are passionate about to the point of obsession.

Many obsessed villains are also mentally ill, though some are merely eccentric or fanatical since they tend to lose control over themselves in regard to what they are highly interested or worried about.