Mark Williams 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 101 Dalmatians (1996) 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.

Harry Potter and the Chamber of Secrets is a 2002 fantasy film directed by Chris Columbus from a screenplay by Steve Kloves, based on the 1998 novel of the same name by J. K. Rowling. Produced by David Heyman, it is the sequel to Harry Potter and the Philosopher's Stone (2001) and the second instalment in the Harry Potter film series. The film stars Daniel Radcliffe as Harry Potter, with Rupert Grint and Emma Watson as his best friends Ron Weasley and Hermione Granger respectively. The story follows Harry's second year at Hogwarts School of Witchcraft and Wizardry, where the Heir of Salazar Slytherin opens the Chamber of Secrets, unleashing a monster that petrifies the school's students.