Marillion /mʌˈrɪlˌjən/ are a British rock band, formed in Aylesbury, Buckinghamshire, England, in 1979. They are known as the most successful band to emerge from the United Kingdom's 1980s neo-progressive rock scene, having sold 15 million albums worldwide.

Their recorded studio output since 1982 is composed of seventeen albums generally regarded in two distinct eras, delineated by the departure of original frontman Fish in late 1988, and the subsequent arrival of replacement Steve Hogarth in early 1989. The band achieved eight Top Ten UK albums between 1983 and 1994, including a Number One album in 1985 with Misplaced Childhood, and during the period the band were fronted by Fish they scored eleven Top 40 hits on the UK Singles Chart, including 1985's "Kayleigh", which reached No. 2 and became their biggest hit single. The first album released with Hogarth, 1989's Seasons End, was another Top Ten hit, and albums continued to chart well until their departure from EMI following the release of their 1996 live album Made Again and the dissipation of the band's mainstream popularity in the late 1990s; save for a resurgence in the mid- to late-2000s, they have essentially been a cult act since then. Marillion have achieved a further twelve Top 40 hit singles in the UK with Hogarth, including 2004's "You're Gone", which charted at No. 7 and is the biggest hit of his tenure. The band continue to tour internationally, and were ranked 38th in Classic Rock's "50 Best Live Acts of All Time" in 2008.