Knightmare is a British children's adventure game show, created by Tim Child and broadcast over eight series on CITV from 7 September 1987 to 11 November 1994. The general format of the show consists of a team of four children – one who takes on the game, and three acting as their guide and advisers – attempting to complete a quest within a fantasy medieval environment, traversing a large dungeon and using their wits to overcome puzzles, obstacles and the unusual characters they meet along the journey.

The show is most notable for its use of blue screen chroma key, an idea Child utilised upon seeing it being put to use in weather forecasts at the time the programme began, as well as its use of 'virtual reality' interactive gameplay on television and the high level of difficulty faced by every team. Broadcast to high viewing figures throughout its original run, it garnered a cult status amongst fans since its final television episode in 1994. It was revived for a one-off special by YouTube in August 2013.