Donnerjack is a science fiction novel begun by American author Roger Zelazny and completed after his death by his companion Jane Lindskold.
The eponymous John Donnerjack is one of the creators of Virtu, and a peerless engineer, capable of building just about anything in his virtual reality.
The story follows John's final adventure, where he saves his lover from Death itself, and continues on through the perspective of his son, Jack.
Many aspects of Donnerjack directly parallel famous myths and legends, particularly those conforming to Joseph Campbell's theory of the monomyth.
It is heavily implied throughout the novel that, though humanity experiences it as a virtual reality simulation, Virtu may actually be an unintentional bridge to the magical realms described in mythology.