Mathabar Singh Thapa was the Prime Minister of Nepal and the Commander-In-Chief of the Nepalese Army from 25 December 1843 – 17 May 1845, until he was murdered by his nephew Jung Bahadur Rana. He was the first Mukhtiyar to title himself as a Prime Minister, as per the British convention. He was the nephew of Bhimsen Thapa, who was sentenced to prison after falsely being accused of killing King Rajendra's six months old son. Mathabar Singh Thapa fled to Shimla after the execution of Bhimsen Thapa, to avoid his own execution as he was Bhimsen's nephew. Four years later, the second queen of Rajendra, Queen Rajya Lakshmi, called him back and installed him as the Mukhtiyar, paving the way for him to eventually title himself as the Prime Minister. Mathabar Singh, however, enraged the queen by refusing to make her son, Ranendra Bikram, the king. The queen, in turn, had him shot by his own nephew Janga Bahadur Rana and thereby making him the last dynast of the Thapa dynasty. Mathabir Singh Thapa was killed by his own nephew.

Bhimsen Thapa was a Nepalese statesman who served as the Mukhtiyar and de facto ruler of Nepal from 1806 to 1837. He is widely known as the longest-serving prime minister of Nepal and was inducted into the "National heroes of Nepal" by King Mahendra Bir Bikram Shah.