X Marks the Spot (On Location with The X-Files) is a reference book published by Arsenal Pulp Press in 1999. The book was written by Louisa Gradnitzer and Todd Pittson, who worked as location managers on the first five seasons of The X-Files television series. X Marks the Spot is a guide to the locations they used during that time as well as the experiences they meanwhile had, also including many black-and-white images (mainly photographs but also a few maps) and an introduction by Tom Braidwood.