Slightly off-topic, I was talking with some friends about why is it that Batman seems to be eternally popular despite the changes in times and culture. I felt stupid for not mentioning Batman's #1 trump card immediately: His Rogue's Gallery.

The Joker
Penguin
Two Face
Poison Ivy
Mr. Freeze
Scarecrow
The Riddler
Scarface
Harley Quinn
Ra's al Ghul
Bane
Black Mask
Killer Croc
The Mad Hatter
Solomon Grundy*
Hush
Man-Bat
Firefly
Victor Zsasz

And so many others but those were the ones I remembered directly by memory. (I was going to add Catwoman too, but do people consider her a Bat-villain anymore?) I mean most of those names and their own particular, interesting gimmicks (most with a psychological flavor of some kind to them) is why I think Batman is still popular. You're only as good as your villain. Or Villains actually.

*=Not exclusively a Batman villain (originally a Green Lantern adversary actually) but I remembered him so I'll count him as well.