Thin Lizzy are an Irish rock band formed in Dublin in 1969. Thin Lizzy initially consisted of bass guitarist, lead vocalist and principal songwriter Phil Lynott, drummer Brian Downey, guitarist Eric Bell and organist Eric Wrixon, although Wrixon left after a few months. Bell left at the end of 1973 and was briefly replaced by Gary Moore, who himself was replaced in mid-1974 by twin lead guitarists: Scott Gorham, who remained with the band until their break-up in 1983, and Brian Robertson, who remained with the band until 1978 when Moore re-joined. Moore left a second time and was replaced by Snowy White in 1980, who was himself replaced by John Sykes in 1982. The line-up was augmented by keyboardist Darren Wharton in 1980. The singles "Whiskey in the Jar" (1972), "The Boys Are Back in Town" (1976) and "Waiting for an Alibi" (1979) were international hits, and several Thin Lizzy albums reached the top ten in the UK. The band's music reflects a wide range of influences, including blues, soul music, psychedelic rock and traditional Irish folk music, but is generally classified as hard rock or sometimes heavy metal.

Lynott led the group throughout their fourteen-year recording career of twelve studio albums, writing or co-writing almost all the band's material. He was the first Black Irishman to achieve commercial success in the field of rock music. Thin Lizzy featured several guitarists throughout their history, with Downey and Lynott as the rhythm section, on the drums and bass guitar. As well as being multiracial, the band drew their early members not only from both sides of the Irish border but also from both the Catholic and Protestant communities during The Troubles.

After Lynott's death in 1986, various incarnations of the band emerged over the years based initially around guitarists Gorham and Sykes, though Sykes left the band in 2009. Gorham later continued with a new line-up including Downey. In 2012, Gorham and Downey decided against recording new material as Thin Lizzy so a new band, Black Star Riders, was formed to tour and produce new releases. Thin Lizzy have since reunited for occasional concerts.

Rolling Stone magazine describes the band as distinctly hard rock, "far apart from the braying mid-70s metal pack". AllMusic critic John Dougan has written that "As the band's creative force, Lynott was a more insightful and intelligent writer than many of his ilk, preferring slice-of-life working-class dramas of love and hate influenced by Bob Dylan, Bruce Springsteen and virtually all of the Irish literary tradition."