A Tumblr user, who goes only by the name ABVH, animates Batman art and covers to chilling effect.
The Joker, done in the right way, is the creepiest villain in all of DC. His strange, chaotic mix of twisted humour and sociopathy make him deeply unpredictable — he could, quite literally, do anything at all for the simple reason that he finds it deeply amusing.
Pair that characterisation with talented comic artists and you have some really spooky stuff. Look, for example, at the Joker that comes out from under the pen of Frazer Irving. Brr.
Two talented artists that have been working on Batman since the New 52 relaunch are Patrick Gleason and Greg Capullo — and static, their images are fantastic encapsulations of the Joker's essential wrongness. Animated, they're just that much more.
You can check out ABVH's Tumblr — which contains so much more than just Batman — here.