Bishweshwar Prasad Koirala, better known as B. P. Koirala, was a Nepali revolutionary, political leader, and writer. He was the Prime Minister of Nepal from 1959 to 1960. He led the Nepali Congress, a social democratic political party. He was the grandfather of Bollywood actress Manisha Koirala and the older brother of former prime minister Girija Prasad Koirala and the younger brother of former prime minister Matrika Prasad Koirala.

The Nepali Congress is the oldest democratic socialist political party in Nepal and the largest party in the country. The party has 870,106 members as of the party's 14th general convention in December 2021 making them the largest party by membership in Nepal. Currently the party has started online membership since the emergence of youth leaders in vital post to bring youths into the party.