The Sikorsky H-34 Choctaw (company designation S-58) is a piston-engined military helicopter that was originally designed by American aircraft manufacturer Sikorsky for the United States Navy for service in the anti-submarine warfare (ASW) role. It has seen extended use when adapted to turbine power by the British licensee as the Westland Wessex and Sikorsky as the later S-58T.

Various H-34s served, mostly as medium transports, on every continent with the armed forces of twenty-five countries — from combat in Algeria, the Dominican Republic, Nicaragua, and throughout Southeast Asia, in roles such as saving flood victims, recovering astronauts, fighting fires, and carrying presidents. As one of the last piston-powered helicopter designs before its replacement by turbine-powered types such as the UH-1 Huey and CH-46 Sea Knight, it would see a remarkably long run of 2,108 H-34s produced between 1953 and 1970.