Sergei Mureiko (born 2 July 1970) is a retired heavyweight Greco-Roman wrestler, who until 1996 represented Moldova and then Bulgaria. He competed in the 1996, 2000 and 2004 Olympics and won a bronze medal in 1996. Between 1993 and 2004 he won 11 medals at the world and European championships, often losing to his main rival Aleksandr Karelin. He won his only international title in 1997, in absence of Karelin. Karelin considered Mureiko his most difficult opponent, and believed that he had much luck in their bouts.