| Martti Marttelin | |
| Fullname: | Martti Bertil Marttelin |
| Nickname: | Maratolin |
| Nationality: |  |
| Birth Date: | 1897 6, df=yes |
| Birth Place: | Nummi, Grand Duchy of Finland, Russian Empire |
| Death Place: | Leningrad, Russian SFSR, Soviet Union |
| Height: | 1.76 m |
| Weight: | 66 kg |
| Sport: | Athletics |
| Event: | 10,000 m, marathon |
| Club: | Nummen Kipinä |
| Pb: | 10,000 m – 32:05.0 (1930) Marathon – 2:35.02 (1928) |
Martti Bertil Marttelin (18 June 1897 – 1 March 1940) was a long-distance runner from Finland, who won the bronze medal in the men's marathon at the 1928 Summer Olympics. He was killed in action during World War II.[1]