Iain Matthews (born 16 June 1946) is an English musician and songwriter. He was born Iain Matthew McDonald, in Scunthorpe, Lincolnshire, England. He was known in the 1960s first as Ian McDonald, then as the 1960s progressed, as Ian Matthews. In 1989 he reverted to the original spelling of his first name.

Influenced by both rock and roll and folk music, he has performed mainly as a solo act, although he was a member of Fairport Convention during the early period when they were heavily influenced by American West Coast folk rock. He later had a solo career and fronted the bands Plainsong, Hi-Fi, No Grey Faith, More Than A Song and Matthews' own Southern Comfort.