Oleg Olegovich Kostin (Russian: Олег Олегович Костин; born 6 May 1992) is a Russian swimmer.

He competed in the men's 50 metre butterfly event at the 2017 World Aquatics Championships.

[1][2] At the 2018 European Championships in Glasgow, he won a bronze in the 50 metre butterfly, setting a Russian 50 metre butterfly record of 22.97 seconds.

[3] At the 2023 Russian National Championships, in April at the Palace of Water Sports in Kazan, Kostin set a new Russian record of 22.62 seconds in the 50 metre butterfly in a time trials conducted after the semifinals and before the final and contested by five of the swimmers in the event.

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