Yi Si-yeong (; December 3, 1868 – April 19, 1953) was a Korean politician, independence activist, educator and neo-Confucianist scholar. He was the first vice president of South Korea from 1948 to 1951. Yi resigned after the National Defense Corps incident of 1951. His art names were Seongjae () or Sirimsanin (). Before the JapanâÂÂKorea Treaty of 1910, he had served for Joseon as the Governor of South Pyongan Province and the President of Hansung Law Court.