Sam Spade was the leading character in the novel and movie The Maltese Falcon (1931). The original novel was written by Dashiell Hammett, and was first published as a serial in the pulp magazine Black Mask.
Sam Spade is most closely associated with actor Humphrey Bogart, who played the character in the most famous film version of The Maltese Falcon (this was the third film version of the book, with Spade played by Ricardo Cortez in the 1931 version and with the central character renamed Ted Shane in the second, 1936, version). While Bogart failed to dye his hair to the characteristic blonde called for by the novel, was considered to be too small and dark for the role, and was even slighted for not being enough of a lecher, he turned out not only to have succeeded, but in fact to have presented the archetypal private detective, one which has influenced "film noir" characters ever since. George Segal played Sam Spade, Jr., son of the original, in the 1974 spoof The Black Bird.
On the radio, Sam Spade was played by Edward G. Robinson in a 1943 Lux Radio Theater production, and by Bogart himself in a 1946 Academy Award Theater production, both on CBS. A 1946-1951 radio show called the Adventures of Sam Spade (on ABC, CBS, and NBC), starred Howard Duff (and later, Steve Dunne), and took a considerably more tongue-in-cheek approach to the character.