Do a Google search for "comic book villain" and he'll pop up in the top 3. He's the "Clown Prince of Crime," the quintessential malevolent maniac, and Batman's baddest bad guy, the nefarious Joker. The creation of Bill Finger, Bob Kane and (some say) Jerry Robinson, he is perhaps the best known and most published comic book villain of all time. Interestingly, for being so infamous, the Joker's origins are very hazy, and his actual identity has never been revealed. According to Wikipedia: