Nguyễn Ngọc Thơ was a South Vietnamese politician who was the first vice president of South Vietnam, serving under President Ngô Đình Diệm from 1956 until Diệm's overthrow and assassination in 1963. He also served as the first prime minister of South Vietnam, serving from November 1963 to late January 1964. Thơ was appointed to head a civilian cabinet by the military junta of General Dương Văn Minh, which came to power after overthrowing and assassinating Diệm, the nation's first president. Thơ's rule was marked by a period of confusion and weak government, as the Military Revolutionary Council (MRC) and the civilian cabinet vied for power. Thơ lost his job and retired from politics when Minh's junta was deposed in a January 1964 coup by General Nguyễn Khánh.

In November 1963, President Ngô Đình Diệm and the Personalist Labor Revolutionary Party of the Republic of Vietnam were deposed by a group of CIA-backed Army of the Republic of Vietnam officers who disagreed with Diệm's handling of the Buddhist crisis and the North Vietnamese and Viet Cong threat to South Vietnam. In South Vietnam, the coup was referred to as Cách mạng 1-11-63.