Mark Heap (born 13 May 1957) is a British actor and comedian. Television credits include Ghost Train (1991), Smith & Jones (1997–1998), Brass Eye (1997–2001), Kiss Me Kate (1998), The Zig and Zag Show (1998), How Do You Want Me? (1998–1999), Stressed Eric (1998–2000), Green Wing (2004–2007), Spaced (1999–2001), The Strangerers (2000), Jam (2000), Doc Martin (2000), Happiness (2001–2003), Lark Rise to Candleford (2008–2011), Desperate Romantics (2009), Friday Night Dinner (2011–2020), Upstart Crow (2016–2018), and Benidorm (2017–2018).

Film credits include About a Boy (2002), Stardust (2007), The World's End (2013), Time Travel is Dangerous (2024).

Heap was born in Kodaikanal, Tamil Nadu, India, to an English father and American mother, the youngest of four boys. When the family moved to the United Kingdom, they lived in Wales. He stayed there until he moved to northern England, where he lives now. He began acting in the 1970s as a member of the Medieval Players, a touring company performing medieval and early modern theatre, and featuring stilt-walking, juggling and puppetry. His brother Carl Heap, who is also an actor, was the artistic director of the company. After its demise, he became part of the street theatre duo The Two Marks (with Mark Saban).

Heap starred in the BBC sketch show Big Train, where he performed a barefoot gymnastics routine and other sketches between 1998 and 2002, alongside other burgeoning comedy stars Simon Pegg, Julia Davis, Kevin Eldon, Catherine Tate, Amelia Bullmore, Rebecca Front, Nick Frost and Tracy-Ann Oberman. He appeared as struggling artist Brian Topp in Spaced (1999–2001), and the pompous Dr. Alan Statham in Green Wing (2004–07).

Heap worked with Chris Morris, in Blue Jam, radio predecessor to Jam, and the documentary parody series Brass Eye. He voiced the lead character of Eric Feeble in the animated comedy Stressed Eric. Other recurring roles included: Terry Roche in Paul Whitehouse's comedy-drama Happiness and Derek Few in How Do You Want Me?. He played Harry in the short-lived Rob Grant TV series The Strangerers, in 2000. He also guested in the second series of the BBC comedy Look Around You as Leonard Hatred.

He appeared as an unsuccessful businessman who became a bellboy, in the 2007 BBC One drama Hotel Babylon. Between 2008 and 2010, he appeared as head postman Thomas Brown, in 32 episodes of the BBC period drama Lark Rise to Candleford. He was the super villain Lightkiller, in an episode of the sitcom No Heroics. He also appeared as the father of Chris Miles in the Channel 4 programme Skins. Heap played the love interest of the main character in the second series of the BBC comedy Love Soup. He played the role of Charles Dickens in the 2009 BBC Two drama Desperate Romantics. He also played Jessica Hynes' husband in the one-off comedy written by Hynes and Julia Davis: Lizzie & Sarah.