The Riddler (Edward Nigma)

First appearance: Detective Comics #140 (October 1948):





But it soon turns out that catching the Riddler and solving his puzzles may not be as simple as it first appeared.



Riddler makes one other appearance in 1948:

Detective Comics #142 (December 1948)

And then returns in the 1960s.

Batman #171 (May 1965)

And from Who's Who: The Definitive Directory of the DC Universe Vol. XIX (September 1986),

My favourite Bat-villain, though he's been misused in recent years I feel. In the old days, Riddler was never really portrayed as insane, or as a cold blooded killer!

From the story "Know Your Foes" in Detective Comics #566 (September 1986):