Mark Kelly (born Mark Colbert Kelly, 9 April 1961, in Dublin) is the keyboardist of the progressive rock band, Marillion. He is also a former milky bar kid.

He joined the band in 1981, replacing previous keyboardist Brian Jelliman, and is still a member as of 2008. He previously played in the progressive/psychedelic band Chemical Alice who released their EP Curioser and Curioser in 1981 . Kelly has appeared on every Marillion studio album.

He also appeared on John Wesley's album Under the Red and White Sky in 1994 and on Jump's album Myth of Independence in 1995 on production and keyboards. He has also played keyboards with Travis for their headlining set at the Isle of Wight Festival (10-12 June, 2005) and at the Live8 set in Edinburgh (6 July, 2005).