Mark Williams (b. 1959) is a British actor and comedian who appeared as the brother in The StoryTeller episode "Fearnot" and as Horace in 101 Dalmatians. He has also played Arthur Weasley in several Harry Potter films and appeared in two episodes of the famous BBC show Doctor Who as Brian Williams.
Williams' other film credits include The Borrowers, Sheakspeare in Love, and Agent Cody Banks 2: Destination London. TV credits include Red Dwarf (three appearances as Olaf Peterson), Chef!, The Fast SHow, Gormenghast, and "Randall & Hopkirk (Deceased).