Lee Myong-Seung (also Lee Myeong-Seung, ; born August 14, 1979, in Seoul) is a South Korean marathon runner. He set a personal best time of 2:13:25, by finishing ninth at the 2010 Seoul International Marathon. In the same year, he achieved his best career result with a fourth-place finish at the Gyeongju International Marathon, clocking at 2:16:19.
Lee made his official debut for the 2004 Summer Olympics in Athens, where he placed forty-first out of a hundred runners in the marathon, with a time of 2:21:01.
At the 2008 Summer Olympics in Beijing, Lee qualified for the second time in the men's marathon, along with his teammates Kim Yi-Yong and Lee Bong-Ju. He successfully finished the race in eighteenth place by seven seconds ahead of Finland's Janne Holmen, posting his best Olympic career time of 2:14:37.