| Sergei Mamchur | |
| Fullname: | Sergei Nikolaevich Mamchur |
| Birth Date: | 1972 2, df=yes |
| Birth Place: | Dnipropetrovsk, Ukrainian SSR |
| Death Place: | Moscow, Russia |
| Position: | Defender |
| Youthclubs1: | Dnipro-75 Dnipropetrovsk |
| Years1: | 1988–1992 |
| Caps1: | 37 |
| Goals1: | 0 |
| Years2: | 1992 |
| Caps2: | 3 |
| Goals2: | 0 |
| Years3: | 1993–1997 |
| Caps3: | 112 |
| Goals3: | 12 |
| Nationalyears1: | 1991 |
| Nationalteam1: | USSR U20 |
| Nationalyears2: | 1992–1994 |
| Nationalteam2: | Russia U21 |
Sergei Nikolaevich Mamchur (Russian: Серге́й Николаевич Мамчур; 3 February 1972 – 26 December 1997) was a Russian football defender.
He was capped for the USSR U-20 team at the 1991 FIFA World Youth Championship.
He died in his Moscow apartment due to a heart failure. Mamchur was buried in his hometown Dnipro.