A Scottish actor, comedian and author, he is known both for his role as Dr Eddie 'Fitz' Fitzgerald in the TV series Cracker and as Rubeus Hagrid in the Harry Potter films.

He moved into acting in his early twenties, taking the stage name Coltrane (in tribute to jazz saxophonist John Coltrane) and working in theatre and stand-up comedy. He soon moved into films, obtaining roles in a number of movies such as Flash Gordon. On television, he also appeared as Samuel Johnson in Blackadder.

His roles went from strength to strength in the 1990s with the TV series Cracker and a BAFTA award as the stepping stone to parts in bigger films such as the James Bond films GoldenEye and The World Is Not Enough and a major supporting role as half-giant Rubeus Hagrid in the Harry Potter films.