| Biography | Mark Williams (born 22 August 1959) is an English actor, screenwriter and presenter. He is best known as Arthur Weasley in the Harry Potter films, and as one of the stars of the popular BBC sketch show The Fast Show. He also played Brian Williams in the BBC series Doctor Who, and Olaf Petersen in Red Dwarf. More recently he has appeared as the title character in the BBC series Father Brow |