Sergei Afanasyevich Kolosov (Russian: Сергей Афанасьевич Колосов; born May 22, 1986) is a professional Belarusian ice hockey defenceman. He is currently playing with HK Neman Grodno of the Belarusian Extraleague. Kolosov was drafted by the Detroit Red Wings of the National Hockey League (NHL) in 2004, and signed a contract with the team on June 25, 2008.
He played for the Belarusian national team at the 2008 IIHF World Championship. He also participated at the 2010 IIHF World Championship as a member of the Belarus National men's ice hockey team.