X Marks the Spot is a quiz or panel game that has been broadcast on BBC Radio 4 since 1998 which could be likened to be a more light-hearted version of Round Britain Quiz. It was presented by the comedian and author Pete McCarthy until his death in October 2004. The writer and broadcaster David Stafford took over the reins from series 7.

The game consists of three celebrities indentifying four places around the United Kingdom, as well as a supplementary question set in those locations. The four locations join up to form a giant X on the map. Where the two lines cross, a treasure is (metaphorically) hidden. The panel have to identify the treasure using up to four lines of a riddle gained by answering the supplementary questions correctly. Unlike the UK television programme Treasure Hunt, there is no actual buried treasure and the panel do not have to fetch it, merely identify it.

The questions are written by David J. Bodycombe and the programme is an independent production by Hewland International for Radio 4.