Jack of Shadows is a novel combining elements of both science fiction and fantasy written by American author Roger Zelazny. According to him, the name of the book (but not the titular character) was a homage to Jack Vance. In his introduction to the novel he mentioned that he tried to capture some of the exotic landscapes so frequent in Vance's work. Zelazny wrote it in first draft, no rewrites. The novel was serialized in F&SF in 1971 and published in book form that same year. It was nominated for a 1972 Hugo Award and finished #4 in the 1972 Locus Poll for Best Novel.
The text of the serialization and the published book are slightly different. A copy-editing error garbled a conversation between Jack and Morningstar in chapter 6; the correct version appeared in the original magazine appearance and has been reprinted on pages 511–512 of The Collected Stories of Roger Zelazny, Volume 3: This Mortal Mountain, NESFA Press, 2009.