Sher Bahadur Deuba (born June 13, 1946) was the prime minister of Nepal. He was a member of the Nepali Congress party, but was later expelled, and is now a member of the Nepali Congress Democratic Party, which he himself formed. He has served as prime minister three times, from 1995 to 1997, 2001 to 2002, and from June 2 2004 until February 1, 2005.

He became prime minister for the second time when he succeeded Girija Prasad Koirala, who resigned in July, 2001, after the murder of King Birendra and several other royal family members by the crown prince. Deuba was in turn removed by Birendra's successor, King Gyanendra, in October, 2002, after Deuba dissolved Parliament and called for elections. After two other governments and much political protest, and the inability to find another suitable candidate, Gyanendra restored Deuba to the position of prime minister in 2004. In the cabinet formed in 2004, Deuba took charge of most of the major government departments. In July 2004, a new cabinet was formed in which Deuba gave up the finance, interior and other departments. He remains the minister of foreign affairs and defense in addition to being prime minister.

He was removed on February 1, 2005 by King Gyanendra, who dissolved the government for three years. The official reason given was his inability to deal effectively with the Maoist insurgents and end the violence that has plagued the mountain kingdom for the past several years.