Mark Williams (born 22 August 1959) is an English actor, comedian, screenwriter and presenter. He is best known as one of the stars of the popular BBC sketch show The Fast Show, as well as for his role of Arthur Weasley in the Harry Potter films.
Williams was born in Bromsgrove. In 2007 Williams appeared in the film adaptation of Neil Gaiman's Stardust alongside Michelle Pfeiffer, Robert De Niro and Claire Danes.
Williams has also presented several documentary programmes: Mark Williams' Big Bangs on the history of explosives, a follow-up to previous series Mark Williams on the Rails, Industrial Revelations and More Industrial Revelations.