Mahendra Bir Bikram Shah Dev (Nepali: महेन्द्र वीर विक्रम शाह देव; 11 June 1920 – 31 January 1972) was King of Nepal from 13 March 1955 until his death in 1972.

He led the 1960 coup d'état, in which he dismissed the government, jailed other political leaders, suspended the constitution, banned political parties, and established an autocratic royal regime. He ruled the country with his Panchayat system for 28 years until the introduction of multi-party democracy in 1990. During his reign, Nepal experienced a period of industrial, political and economic change which opened it to the rest of the world for the first time, after the 104-year-long reign of the Rana rulers, who kept the country under an isolationist policy, came to an end in 1951.