The National Liberation Movement – Tupamaros (Spanish: Movimiento de Liberación Nacional – Tupamaros, MLN-T) was a Marxist–Leninist urban guerrilla group that operated in Uruguay during the 1960s and 1970s. It was responsible for numerous violent incidents involving left-wing terrorist activities. In 1989, the group was admitted into the Broad Front and a large number of its members joined the Movement of Popular Participation (MPP).

Formed in the early 1960s, the MLN-T sought to create a revolutionary state through armed struggle, taking inspiration from the 1953-59 Cuban Revolution led by Fidel Castro. However, unlike the latter, it conducted its operations in urban areas. The organization gained notoriety for its violent acts of sabotage, bank and armory robberies, assassinations of military and police officers, bombings, and kidnappings of judges, businessmen, diplomats and politicians.

The MLN-T is inextricably linked to its most important leader, Raúl Sendic, and his brand of Marxist politics. José Mujica, who later became President of Uruguay, was also a member. 300 Tupamaros died either in action or in prisons (mostly in 1972), according to officials of the group. About 3,000 Tupamaros were also imprisoned.

Due to the reforms implemented at the beginning of the 20th century during the Batlle era, Uruguay became one of the most prosperous nations in Latin America. Since then, the country has maintained a robust welfare state, progressive social and labor laws, and a high quality of life, earning it the nickname 'The Switzerland of the Americas'. Additionally, since the mid-19th century, Uruguay has experienced a massive wave of European migration, particularly from Italians and Spaniards, who significantly shaped its culture and society.

During both World Wars, the Uruguayan economy was significantly boosted by the sale of raw materials to countries involved in the conflicts. However, from the mid-1950s onward, as global demand for agricultural products declined and Europe underwent reconstruction, exports fell, leading to a severe economic crisis. The Tupamaros emerged during this period of instability, attracting professionals, workers, trade unionists, and students. Unlike other guerrilla groups formed during the Cold War, the MLN-T was primarily composed revolutionary leftist individuals from the upper-middle and upper classes.

According to one of its top members, Eleuterio Fernández Huidobro, the formal founding of the MLN-T took place in 1965; however, the organization's first action was the theft of weapons and ammunition from the Tiro Suizo, a shooting range in Nueva Helvecia, in 1963. A year earlier, nursing student Dora Isabel López de Oricchio was shot dead during an assault on the headquarters of a union association, carried out by a group led by Raúl Sendic Antonaccio. This event is considered one of the earliest acts attributed to far-left violence.

At the outset, the organization did not operate under its name, instead operating in a more anonymous manner. In November 1964, leaflets were circulated for the first time that read TNT: Tupamaros no transamos. 'Transamos'—the first-person plural form of the verb 'transar'—is slang from the lunfardo of Uruguayan Spanish, used to mean 'compromise' or 'settle.' It often carries a negative connotation, implying a refusal to compromise on principles or values. The organization was named after the revolutionary Túpac Amaru II, who in 1780 led a major indigenous revolt against the Viceroyalty of Peru.

In August 1965, the organization issued a leaflet under its name for the first time, claiming responsibility for an explosion at the entrance to the Bayer company's headquarters in Montevideo.