The Revolutionary Front for an Independent East Timor (Portuguese: Frente Revolucionária do Timor-Leste Independente, abbreviated as Fretilin) is a centre-left political party and former national liberation movement in Timor-Leste. It presently holds 19 of 65 seats in the National Parliament. Fretilin formed the government in East Timor until its independence in 2002. It obtained the presidency in 2017 under Francisco Guterres but lost in the 2022 East Timorese presidential election.

Fretilin began as a resistance movement that fought for the independence of East Timor from Portugal in 1974 and proceeded to resist the Indonesian occupation of East Timor until 1999. Upon gaining her total independence in 2002, Fretilin became one of several parties competing for power in a multi-party system.

Fretilin was founded on 20 May 1974 as the Timorese Social Democratic Association (ASDT). The ASDT renamed itself to Fretilin on 11 September 1974 and took a more radical stance, proclaiming itself the “sole legitimate representative” of the East Timorese people. In response to a coup by the Timorese Democratic Union (UDT) on 11 August 1975, Fretilin hastily formed an armed wing called Falintil, which emerged victorious after a three week civil war. Falintil would continue to wage war against the ABRI during its invasion on 7 December 1975 and ensuing occupation.

Fretilin formally declared East Timor's independence from Portugal on 28 November 1975 and inaugurated an 18-member cabinet with members of the Fretilin Central Committee with Francisco Xavier do Amaral as president and Nicolau dos Reis Lobato as both vice president and prime minister. The two men fell out as the pressures from the occupation escalated, and in September 1977 Lobato had do Amaral arrested for "high treason". On 31 December 1978, Lobato, do Amaral's successor as president, was killed by the Indonesian forces. He was succeeded by Mau Lear, who served until he was also tracked down and executed by Indonesian forces on 2 February 1979.

Fretilin came under enormous pressure in the late 1970s. From September 1977 to February 1979, only three of the 52 members of Fretilin's Central Committee survived.

Fretilin survived despite the military collapse, and was slowly rebuilt under the relatively moderate and nationalist leadership of Xanana Gusmão.

Between March 1981 and April 1984, Fretilin was known as Partido Marxista–Leninista Fretilin (PMLF), and Marxism-Leninism was officially declared the party's ideology. The name was changed back in 1984; furthermore, its revolutionary politics was abandoned in order to further national unity and acquire the support of the UDT and the Catholic Church.

In the first elections, held in 2001, the year before independence, Fretilin polled 57.4% of the vote and took 55 seats in the 88-seat Assembly. While this gave the party a working majority, it fell short of the two-thirds majority it had hoped for to dictate the drafting of a national constitution.