Nam Yoo-sun (also Nam Yu-seon, Korean: 남 유선; born July 23, 1985) is a South Korean swimmer, who specialized in individual medley events. She is a three-time Olympian (2000, 2004, and 2008), a fourth-place finalist at the 2002 Asian Games in Busan, and a two-time medalist in the individual medley (both 200 and 400 m) at the 2005 East Asian Games in Macau, China. Nam became the first South Korean swimmer in history to reach an Olympic final, until Park Tae-Hwan won the nation's first ever swimming medal at the succeeding Olympics in 2008.