| Jack Brennan | |
| Fullname: | John Brennan[1] |
| Birth Date: | 13 December 1892 |
| Birth Place: | Manchester, England |
| Height: | [2] |
| Position: | Half back |
| Youthclubs1: | Ancoats Lads Club |
| Clubs1: | Hollinwood United |
| Clubs2: | Denton |
| Years3: | 1912–1913 |
| Clubs3: | Glossop |
| Caps3: | 21 |
| Goals3: | 0 |
| Years4: | 1913–1914 |
| Clubs4: | Bradford City |
| Caps4: | 11 |
| Goals4: | 0 |
| Years5: | 1914–1922 |
| Clubs5: | Manchester City |
| Caps5: | 56 |
| Goals5: | 0 |
| Years6: | 1922–1923 |
| Clubs6: | Rochdale |
| Caps6: | 0 |
| Goals6: | 0 |
| Totalcaps: | 88 |
| Totalgoals: | 0 |
John Brennan (13 December 1892 – 13 August 1942) was an English professional footballer who played as a half back. He made 88 appearances in the Football League without scoring.
Born in Manchester, Brennan played for Ancoats Lads Club, Hollinwood United, Denton, Glossop, Bradford City, Manchester City and Rochdale.[3] For Bradford City, he made 11 appearances in the Football League.[4] For Manchester City, he made 56 appearances in the Football League, and 4 appearances in the FA Cup.[5] Brennan was also part of Great Britain's squad for the 1920 Summer Olympics, but he did not play in any matches.[6]