What happened to the president of south Vietnam during the Vietnam war and who replaced him?

Nguyễn Cao Ky was Prime Minister until the fall of Saigon. He left the country and settled in Venice, California, where he ran a chain of liquor stores.

KY and President Nguyễn Văn Thiệu worked hand in hand through a series of intrigues to maintain control of South Vietnam, winning American backing. They were both a couple of cowboys.

Nguyễn Văn Thiệu was evacuated by U.S. helicopter in 1975 with millions in gold. He settled in Massachusetts, where he died in 2001. He was always a marked man. Many Vietnamese ex-patriots blamed his corrupt leadership for the downfall of their country.

Nobody replaced them, as South Vietnam ceased to be.