Decked out in a bright green body suit with purple accents and maniacally spouting twisted riddles between piercing giggles, The Riddler is definitely one of the wilder villains in the Batman universe. This queerly quizzical character has had a very long career, with incarnations both in print and on the big and small screens. He made his first appearance in 1948, and has been going strong ever since. According to Wikipedia:
"The Riddler is obsessed with riddles, puzzles, and word games. He delights in forewarning both Batman and the police of his capers by sending them complex clues. With this self-conscious use of a gimmick, the Riddler's crimes are flamboyant and ostentatious."
Detective Comics #140 (1948)
Riddler's 1st Appearance
Riddler's criminal modus operandi is so deeply ingrained into his personality
that he is virtually powerless to stop himself from acting it out (as shown in
his third comic book appearance). He cannot simply kill his opponents when he
has the upper hand; he has to put them in a deathtrap to see if he can devise
a life and death intellectual challenge that the hero cannot solve and escape.
However, unlike many of Batman's themed enemies, Riddler's compulsion is quite
flexible, allowing him to commit any crime as long as he can describe it in a
riddle or puzzle."