John Ronald Simm is an English actor. He is best known for his roles as Sam Tyler in Life on Mars and the Master in Doctor Who. He has starred in television dramas such as Cracker, The Lakes, Sex Traffic, State of Play, Crime and Punishment, and Exile. He has been nominated twice for the BAFTA Award for Best Actor and is a Laurence Olivier Award nominee. He has appeared in films such as Wonderland, Human Traffic, and 24 Hour Party People. In 2010, he played Hamlet at the Crucible Theatre.