Sedef Köktentürk (born 22 July 1974) is a Turkish former windsurfer, who specialized in the RS:X class.

[1] She was the country's top female windsurfer for the 2008 Summer Olympics, finishing last of the 27-woman fleet.

[3][4] Köktentürk competed for the Turkish sailing squad, as a lone female, in the inaugural women's RS:X class at the 2008 Summer Olympics in Beijing.

[5] Building up to her Olympic selection, she formally accepted a berth forfeited by Germany, as the next highest-ranked windsurfer vying for qualification, at the class-associated Worlds nearly eight months earlier in Auckland, New Zealand.

Köktentürk clearly struggled to catch a large fleet of windsurfers from behind under breezy conditions with marks lower than the top 20 and an unanticipated eighth-leg exit at the end of ten-race series, sitting her in last with 232 net points.