Oh Eun-Sun (born March 5, 1966) is a South Korean female mountaineer. She is the first Korean woman to climb the Seven Summits.
On April 27, 2010, she reached the Annapurna summit, the mountain with the highest fatality/death rate. Oh claimed she had climbed all fourteen eight-thousanders, which would have made her the first woman to achieve this feat, but her claim to have ascended Kangchenjunga was disputed by multiple experts. Oh Eun-Sun later admitted that she had to stop a few meters below the Kangchenjunga summit — therefore the Korean Alpine Federation ruled that Oh did not climb that peak, and the renowned mountaineering site ExplorersWeb considered that Edurne Pasaban is the first woman that has climbed all fourteen peaks.