| Marcin Kaczmarek | |
| Fullname: | Marcin Kaczmarek |
| Strokes: | Butterfly |
| Club: | AZS-AWF Gdańsk |
| Birth Date: | 25 June 1977 |
| Birth Place: | Pisz, Warmińsko-Mazurskie |
Marcin Kaczmarek (born 25 June 1977 in Pisz, Warmińsko-Mazurskie) is a retired butterfly swimmer from Poland, who competed for his native country at the 2000 Summer Olympics in Sydney, Australia.
A member of AZS-AWF Gdańsk he is best known for winning the bronze medal at the 1997 European Swimming Championships in the men's 4×100 m medley relay, alongside Mariusz Siembida, Marek Krawczyk and Bartosz Kizierowski.