Harry Otto Fischer (1910–1986) was an American science fiction writer and fan best known for helping his college friend Fritz Leiber create the sword and sorcery heroes Fafhrd and the Gray Mouser and their imaginary world of Nehwon.
The fictional heroes were based vaguely on their creators, the barbarian Fafhrd on the tall Leiber, and the thief The Gray Mouser on Fischer.
During 1937, Fischer and Leiber designed a board game set in this fantasy world and each began composing a story with the same setting, Fischer's being "The Lords of Quarmall" and Leiber's "The Adventure of the Grain Ships."
[1] The first professional publication of a story featuring the heroes and their setting was "Two Sought Adventure", in Unknown magazine during 1939.
Fischer also wrote "The Childhood and Youth of the Gray Mouser," published during 1978 in The Dragon #18.