Sergey Ostapchuk (Russian: Серге́й Остапчук; born 10 February 1976) is a retired Russian swimmer who won two bronze medals at the World and European championships in 1999.^[1] He also competed in the 100 m and 200 m backstroke events at the 1996 and 2000 Summer Olympics but did not reach the finals.^[2]

He has retired from senior swimming, but is still competing in the masters category. He lives in Vladivostok.^[3]