Who is your all-time favourite character that is clinnically (or otherwise) insane? This could be from video games, books, television, pretty much any fictional work.

And what traits do you like to see in crazy characters? What would make them more insane, intimidating, lovable, etc.?

I find Kefka to be pretty fun to read his words and explore his mind. I haven't played Far Cry 3 yet, so I can't say the same for Vaas. I also like to see insane characters possess some kind of power, because, let's face it, you just pity crazy people with no power. You have to fear them, IMO. You also should be entertained by their odd dialogue and thought process.