
Mark Williams (born August 22, 1959) is an English actor, comedian, presenter and screenwriter. He first achieved widespread recognition as one of the central performers in the popular BBC sketch show The Fast Show. His film roles include Horace in the 1996 adaptation of 101 Dalmatians and Arthur Weasley in seven of the Harry Potter films. He made recurring appearances as Brian Williams in the BBC television series Doctor Who and as Olaf Petersen in Red Dwarf. Since 2013, Williams has portrayed the title character in the long-running BBC series loosely based on the Father Brown short stories by G. K. Chesterton.

Midsomer Murders
TV • 1997

Doctor Who
TV • 2005

The One Show
TV • 2006

Casualty
TV • 1986

Top of the Pops
TV • 1964

Father Brown
TV • 2013

Agatha Christie's Marple
TV • 2004

Peak Practice
TV • 1993

Merlin
TV • 2008

New Tricks
TV • 2004

Hustle
TV • 2004

Red Dwarf
TV • 1988

Harry Potter and the Chamber of Secrets
MOVIE • 2002

Loose Women
TV • 1999

The Musketeers
TV • 2014

Harry Potter and the Half-Blood Prince
MOVIE • 2009

Harry Potter and the Goblet of Fire
MOVIE • 2005

Sister Boniface Mysteries
TV • 2022