Marillion are a British neo prog band, formed in Aylesbury, Buckinghamshire, in 1979. They emerged from the post-punk music scene in Britain and existed as a bridge between the styles of punk rock and classic progressive rock, becoming the most commercially successful neo-prog band of the 1980s.

Marillion released their debut single "Market Square Heroes" in 1982, followed by their first album Script for a Jester's Tear in 1983. They have released 20 studio albums in total. The band's history is generally regarded in two distinct eras, separated by the departure of original lead singer Fish in late 1988 and the arrival of his replacement Steve Hogarth in early 1989. Marillion achieved eight Top 10 UK albums between 1983 and 1994, including a No. 1 album in 1985 with Misplaced Childhood. The album also produced two UK Top 10 singles in "Kayleigh" (No. 2) and "Lavender" (No. 5), while the follow-up album, 1987's Clutching at Straws (the last studio album with Fish), included another UK Top 10 single "Incommunicado" (No. 6). Altogether, during the Fish era, Marillion scored 11 Top 40 hits on the UK Singles Chart. "Kayleigh" also entered the Billboard Hot 100 in the United States.

Marillion's first album with Hogarth, 1989's Seasons End, was another Top 10 hit, and albums continued to chart well until their departure from EMI Records 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. Since the arrival of Hogarth, Marillion have achieved a further 12 Top 40 hit singles in the UK, including 2004's "You're Gone" from the album Marbles, which charted at No. 7 and is the biggest hit of the Hogarth era. In 2016, the album Fuck Everyone and Run (F E A R) returned them to the UK Albums Chart Top 10 for the first time since 1994's Brave. Their most recent album, 2022's An Hour Before It's Dark, entered the UK Albums Chart at No. 2, their highest chart position since Clutching at Straws in 1987. Marillion continue to tour internationally, becoming ranked 38th in Classic Rock's "50 Best Live Acts of All Time" in 2008.

Despite unpopularity in the mainstream media and a consistently unfashionable status within the British music industry, Marillion have maintained a very loyal international fanbase, becoming widely acknowledged as playing a pioneering role in the development of crowdfunding and fan-funded music. They have sold over 15 million albums worldwide.