The Unknown Five is an anthology of fantasy fiction short stories edited by D. R. Bensen and illustrated by Edd Cartier, the fourth of a number of anthologies drawing their contents from the classic magazine Unknown of the 1930s-40s. It was first published in paperback by Pyramid Books in January 1964. The cover title of this first edition was The Unknown 5; the numeral was spelled out on the title page and copyright statement. The book was reprinted by Jove/HBJ in October 1978.