The National Union of Freedom Fighters (NUFF) was an armed Marxist revolutionary group in Trinidad and Tobago. Active in the aftermath of the 1970 Black Power Revolution, the group fought a guerrilla warfare campaign to overthrow the government of Prime Minister Eric Williams following the failed Black Power uprising and an unsuccessful mutiny in the Trinidad and Tobago Regiment.

NUFF formed out of the Western United Liberation Front (WOLF), a loose grouping of largely unemployed men in the western suburbs of Port of Spain. After the failed mutiny, members of WOLF decided to overthrow the government through armed rebellion. In 1971 they attempted to assassinate the lead prosecutor of the mutineers and a coast guard officer who helped suppress the army mutiny.

The group drew disaffected members of the National Joint Action Committee (NJAC), the country's leading Black Power organisation, and established a training camp in south Trinidad. In 1972 and 1973 NUFF attacked police posts to acquire weapons, robbed banks, and carried out an insurgent campaign against the government. With improved intelligence capabilities, the government was able to track the group and eventually killed or captured most of its leadership. Eighteen NUFF members and three policemen were killed during the insurgency.

Ideologically NUFF was anti-imperialist and anti-capitalist, and opposed both the foreign investors who controlled much of the economy and the local economic elites. They were notable for the extent to which women played an active role in the organisation, and included women among its guerrilla fighters. They were the only group to sustain a guerrilla insurgency in the modern English-speaking Caribbean over an extended period. Former members went on to play a role in the political process, while others were involved in the 1990 coup d'état attempt by the Jamaat al Muslimeen.