| Bob Mercer | |
| Fullname: | Robert Mercer |
| Birth Date: | 21 September 1889[1] |
| Birth Place: | Avonbridge, Scotland |
| Death Place: | Selkirk, Scotland |
| Position: | Centre back |
| Youthclubs1: | Gala Hailes Villa |
| Years1: | 1907–1908 |
| Years2: | 1908–1909 |
| Years3: | 1909–1921 |
| Years4: | 1921–1922 |
| Caps2: | 18 |
| Caps3: | 242 |
| Caps4: | 70 |
| Goals2: | 1 |
| Goals3: | 23 |
| Goals4: | 6 |
| Nationalyears1: | 1912–1913 |
| Nationalteam1: | Scottish League XI |
| Nationalcaps1: | 5 |
| Nationalgoals1: | 1 |
| Nationalyears2: | 1912–1913 |
| Nationalteam2: | Scotland |
| Nationalcaps2: | 2 |
| Nationalgoals2: | 0 |
Robert Mercer (21 September 1889 – 23 April 1926) was a Scottish footballer who played for Leith Athletic, Heart of Midlothian, Dunfermline Athletic and Scotland.[2] Mercer served in the British armed forces during the First World War, but he was a victim of a gas attack and did not fully recover.