Since a bunch of people here are probably going to go with Gotham, I thought I'd tap another one of my fandom interests for this post...
I'm not particularly sure of when I got into
My Little Pony: Friendship is Magic - all I recall is that it was somewhere between the end of Season 3 and the beginning of Season 4. Animation outlets wouldn't shut up about it, all my friends on the 'net were into it, blah blah blah. Long story short - watched it, thought it was alright, read some of the fanfic, started liking the world of Equestria a whole lot more.
Let's get something clear here: this show isn't the second coming of
Batman: The Animated Series (which, in any case, would be Gargoyles), but it's got potential. At least, more potential than the previous generations of
My Little Pony did. The villains aren't allowed to really cut loose, since it's a kid's show and everything (and a lot of the more adventure-centric stories have
seriously bad plot holes), but the writing staff of both the show and the tie-in comics managed to infuse their villains with enough personality and unique character designs to make up for it.
MLP: FIM is the kind of series where the line between "villain" and "jerk" tends to become rather blurry, and I have neither the patience nor the space here to list all of the characters who belong in both categories, so I think I'll go with the ones that grabbed my imagination the most.

(Sidenote: I like to imagine that there can, in fact, be an in-universe situation where all of these chumps will happily hang out together.)
( Four legs bad, two legs badder! )