Ranabir Singh Thapa also spelled Ranbir, Ranavir or Ranvir also known by the late ascetic name Swami Abhayananda was a Nepalese army general, prominent politician and minister of state. In 1837, he became acting Mukhtiyar of Nepal for a brief period. He was a prominent member of Thapa dynasty. He later turned ascetic and was known by the Sanyasi name Swami Abhayananda.

Thapa dynasty or Thapa noble family also known as Dynasty of Borlang was a Chhetri political family that handled Nepali administration affairs between 1806 and 1837 A.D. and 1843 to 1845 A.D. as Mukhtiyar. This was one of the four noble families to be involved in the active politics of the Kingdom of Nepal, along with the Shah dynasty, Basnyat family, and the Pande dynasty before the rise of the Rana dynastyor Kunwar family. At the end of 18th century, Thapas had extreme dominance over Nepalese Darbar politics alternatively contesting for central power against the Pande family. Bir Bhadra Thapa was a Thapa of Chhetri group and leading Bharadar during Unification of Nepal. His grandson Bhimsen Thapa became Mukhtiyar of Nepal and established Thapa dynasty to the dominating position of central court politics of Nepal.