In 1965, Holm played Richard III in the BBCs serialisation of the Wars of the Roses plays, and gradually made a name for himself with minor roles in films such as Oh! What a Lovely War (1969), Nicholas and Alexandra (1971), Mary, Queen of Scots (1971) and Young Winston[?] (1972). By the time of Alien (1979) and Chariots of Fire (1981), he was a major star in the UK, and his reputation gradually spread to the USA. He continued to perform Shakespeare, and appeared with Kenneth Branagh in Henry V[?] (1989) and as Polonius to Mel Gibson's Hamlet.
In 1991 he married, as his third wife, popular actress Penelope Wilton, and they appeared together in The Borrowers[?] (1993) on British television. In 1998, Holm was knighted for his services to acting.
In 2001, he appeared as Bilbo Baggins in the blockbuster film The Lord of the Rings: The Fellowship of the Ring, having previously played Bilbo's nephew Frodo Baggins in the 1981 BBC Radio adaptation of The Lord of the Rings.
His is one of the most familiar voices in Britain, having been heard in countless TV documentaries and commercials.