Land of Unreason is a fantasy novel written by Fletcher Pratt and L. Sprague de Camp. It was first published in the fantasy magazine Unknown Worlds for October, 1941 as "The Land of Unreason". Revised and expanded, it was first published in book form by Henry Holt and Company in 1942. It has been reprinted numerous times since by various publishers, most notably by Ballantine Books in January 1970 as the tenth volume of the Ballantine Adult Fantasy series.