Ngô Đình Diệm (January 3, 1901 – 2 November 1963) is the first president of South Vietnam (1955–1963).

In the wake of the French withdrawal from Indochina as a result of the 1954 Geneva Accords, Diệm leads the effort to create the Republic of Vietnam.

Accruing considerable US support due to his staunch anti-communism, he achieves victory in a fraudulent 1955 plebiscite.

A Roman Catholic, Diệm pursues biased and religiously oppressive policies against the Republic's Montagnard natives and its Buddhist majority that are met with protests, epitomized in Malcolm Browne's Pulitzer Prize winning photograph of the self-immolation of Buddhist monk Thích Quảng Đức in 1963.

Amid religious protests, Diệm loses the backing of his US patrons and is assassinated, along with his brother, Ngô Đình Nhu by Nguyễn Văn Nhung, the aide of ARVN General Dương Văn Minh on 2 November 1963, during a coup d'état that deposes his government.