| Yun Bo-seon | |
| Order: | 4th |
| Office: | President of South Korea |
| Term Start: | August 13, 1960 |
| Term End: | March 22, 1962 |
| Predecessor: | Syngman Rhee |
| Successor: | Park Chung-hee |
| Birth Date: | August 26, 1897 |
| Birth Place: | Asan, South Chungcheong, South Korea |
| Nationality: | Korean |
| Spouse: | Gong Deok-gui |
| Party: | Democratic |
| Korean name | |
| Hangul: | 윤보선 |
| Hanja: | 尹潽善 |
| Rr: | Yun Boseon |
| Mr: | Yun Posŏn |
| Hangulho: | 해위 |
| Hanjaho: | 海葦 |
| Tablewidth: | 265 |
| Color: | lavender |
Yun Bo-seon (August 26, 1897 – July 18, 1990) was the President of South Korea from 1960 to 1962.
Born in Asan, Chungcheongnam-do, Yun graduated with an M.A. from the University of Edinburgh in 1930. He entered politics after Japanese occupation ended in 1945, with Syngman Rhee being his mentor. In 1948, Yun was appointed by Rhee as mayor of Seoul. A year later, he was appointed as the Minister of Commerce and Industry. Soon, he started to disagree with Rhee's authoritarian policies. He then served as president of the Red Cross Society, before being elected to the National Assembly in 1954. A year later, he founded the opposition Democratic Party along with several others.
After Rhee's government was ousted by a student-led pro-democracy uprising, Yun was elected president on August 13, 1960. He was merely a figurehead, as South Korea had switched to a parliamentary system in response to the authoritarian excesses of Rhee's regime. After Park Chung Hee's coup in 1961, he stayed on briefly to provide legitimacy to the regime, but resigned on March 22, 1962. He opposed Park's authoritarian rule and ran for president twice in 1963 and 1967, losing each time. After receiving suspended sentences several times for anti-government activities, Yun retired from politics in 1980 and focused primarily on cultural activities until his death from diabetic conditions and high blood pressure in 1990. His descendants currently live in the United States.