| Deacon Donahue | |
| Position: | Pitcher |
| Bats: | Right |
| Throws: | Right |
| Birth Date: | 23 June 1920 |
| Birth Place: | Chicago, Illinois |
| Death Place: | Glenview, Illinois |
| Debutleague: | MLB |
| Debutdate: | September 16 |
| Debutyear: | 1943 |
| Debutteam: | Philadelphia Phillies |
| Finalleague: | MLB |
| Finaldate: | May 26 |
| Finalyear: | 1944 |
| Finalteam: | Philadelphia Phillies |
| Statleague: | MLB |
| Stat1label: | Win–loss record |
| Stat1value: | 0–2 |
| Stat2label: | Earned run average |
| Stat2value: | 6.75 |
| Stat3label: | Strikeouts |
| Stat3value: | 3 |
| Teams: | |
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 6inchesft0inchesin (ftin), 180lb, Donahue batted and threw right-handed. He was born in Chicago, Illinois.
Donahue was one of several players who only appeared in the majors during World War II. In eight relief appearances, he posted a 0–2 record with a 6.75 earned run average with no saves, giving up 11 runs (one unearned) on 22 hits and three walks while striking out three in 13 innings of work.
Following his baseball career, Donahue worked as a movie theatre projectionist in the Chicago area for 40 years. He died in Glenview, Illinois, at the age of 87.