Mark Heap (born 4 October 1952) is an English actor best known for a variety of television comedy roles including struggling artist Brian Topp in Spaced, the pompous Dr. Alan Statham in Green Wing, and various roles in the sketch shows Big Train and Jam. Earlier he was a member of the street theatre duo The Two Marks who appeared on Saturday morning children's television Ghost Train in the early nineties. In 2002 Mark played Marmite the Dwarf, in the short-lived BBC Radio 4 sitcom The Sofa of Time written by and starring Nick Frost and Matt King.

He was also in the radio predecessor of Jam, Blue Jam, and Chris Morris's controversial "TV documentary" parody Brass Eye. In this he participated in the famous 'Good Aids/Bad Aids' sketch, in which, after learning that Heap's character has caught 'Bad Aids' from his boyfriend and not, as he had thought, 'Good Aids' from a blood transfusion, Chris Morris asks for him to be removed from the studio, a suggestion met with loud cheers from the audience. He voiced the eponymous Eric in the animated comedy Stressed Eric but his voice was replaced by that of Hank Azaria when the show aired in America. Other recurring roles included Terry Roche in Paul Whitehouse's comedy-drama Happiness and Derek Few in How Do You Want Me?. He played Eliza's husband in The Eliza Stories (by Barry Pain, adapted by Jonathan Dryden Taylor), broadcast on BBC Radio 4, October 2006. He has also featured in the 80's UK game show 321, in a stage magic double act called "The Two Marks".

In the film About a Boy, Heap played a school teacher. Alongside Kevin Eldon, he played 'Man with dog' in Tim Burton's 2005 film Charlie and the Chocolate Factory. He also guested in the second series of the BBC comedy Look Around You as Leonard Hatred, and starred in the music video for Four Tet's single "Smile Around The Face" in 2005. Heap also played a minor role in the 2006 film Confetti as the marriage registrar. He played an injured fairground patron in Tunnel of Love (2004), which also starred Jack Dee. In March 2007 he appeared in the BBC One sitcom Hotel Babylon as an unsuccessful businessman who became a bellboy. He plays the part of the prince Tertius in the 2007 film Stardust. In 2008 he appeared in the BBC period drama Lark Rise to Candleford in the role of Thomas Brown, the Post Office's head postman.

Started out as a street entertainer, winning an award for his comedy juggling act.