Jung Bahadur, also spelled Jang Bahadur, (born June 18, 1817, Kāthmāndu, Nepal—died Feb. 25, 1877, Kāthmāndu), prime minister and virtual ruler of Nepal from 1846 to 1877, who established the powerful Rana dynasty of hereditary prime ministers, an office that remained in his family until 1951.

Jung Bahadur, a man of great courage and ability, gained control over the government after killing a usurper, Gagan Singh, who in 1846 had plotted with the junior queen to become prime minister and place her son on the throne. Subsequently, he deposed and exiled both the king and the queen after they had attempted to have him assassinated. He was named prime minister for life and given the hereditary title of Rana. During 1850–51 he visited England. He remained a firm friend of the British throughout his life.

Jung Bahadur’s diplomatic skill and conciliatory policy helped Nepal remain independent while the rest of the Indian subcontinent came under British rule. During the Indian Mutiny of 1857–58 he sent a contingent of Gurkha soldiers to aid the British, thus establishing a tradition of Gurkha military service in the British army. He also did much to improve and modernize the administration of the country and revised the old penal code. Although he attempted to abolish suttee, three of his widows immolated themselves on his funeral pyre.

Once he was appointed hereditary prime minister, Jung Bahadur believed it essential for the security of the state that he should be succeeded by a fully adult and capable man. Accordingly, he devised an order of succession by means of which the office passed not from father to son but rather from brother to brother within the family. In the second generation it passed to the sons of all his brothers in order of age and in a similar manner in succeeding generations. At his death Jung Bahadur was thus succeeded by his younger brother Rana Udip Singh. The office of prime minister remained in the Rana family through the first half of the 20th century, the last hereditary prime minister, Mohun, retiring in 1951. The Rana family continued, however, to remain extremely powerful. In February 1970 the crown prince Birendra, who in 1972 became king of Nepal, married a woman of the Rana family, who became his queen.