| Dummy Deegan | |
| Position: | Pitcher |
| Bats: | Unknown |
| Throws: | Right |
| Birth Date: | 16 November 1874 |
| Birth Place: | Bronx, New York |
| Death Place: | Bronx, New York |
| Debutleague: | MLB |
| Debutdate: | August 3 |
| Debutyear: | 1901 |
| Debutteam: | New York Giants |
| Finalleague: | MLB |
| Finaldate: | August 9 |
| Finalyear: | 1901 |
| Finalteam: | New York Giants |
| Statleague: | MLB |
| Stat1label: | Innings pitched |
| Stat1value: | 17 |
| Stat2label: | Win–loss record |
| Stat2value: | 0–1 |
| Stat3label: | Earned run average |
| Stat3value: | 6.35 |
| Teams: | |
William Joseph "Dummy" Deegan (November 16, 1874 – May 17, 1957) was an American professional baseball pitcher. In 1901, he played in two games for the New York Giants of Major League Baseball.
Deegan, nicknamed "Dummy" for being a deaf-mute, was one of three pitchers on the Giants staff in 1901 with that nickname; the other two being Dummy Leitner and Dummy Taylor.