John Stephen Michael "Deacon" Donahue (June 23, 1920 – March 6, 2008) was a relief pitcher in Major League Baseball who played from 1943 through 1944 for the Philadelphia Phillies.

Listed at 6 ft 0 in (1.83 m), 180 lb (82 kg), Donahue batted and threw right-handed.

Donahue was one of several players who only appeared in the majors during World War II.

Following his baseball career, Donahue worked as a movie theatre projectionist in the Chicago area for 40 years.

This biographical article relating to an American baseball pitcher born in the 1920s is a stub.