Serhiy Leonidovych Fesenko (Сергей Леонидович Фесенко, born 29 January 1959) is a Soviet swimmer and Olympic champion.

He competed at the 1980 Olympic Games in Moscow, where he won the gold medal in 200 m butterfly.

Silver medalist of the Olympic Games 1980 in 400 meter individual medley (4.23,43).

Bronze in 1982 FINA World Swimming Championships in 400 meter individual medley.

He's a student at Drury University, and NCAA D2 individual and team champion for 2006–2007, 2007–2008 and 2008-2009 collegiate seasons.