is there any novel based on this film?
Yes. By Wayland Drew
Willow (film)
Wayland Drew adapted Lucas's story into a film novel, providing additional background information to several major characters and various additional scenes,
who played willow's wife in the movie willow UNANSWERABLE is it based on a novel? No
wiki:13508353
Willow (film) [SEP] Novels
Wayland Drew adapted Lucas's story into a film novel, providing additional background information to several major characters and various additional scenes, including an encounter with a lake monster near Razel's island which was filmed, but ultimately not used in the movie. A segment of that scene's filmed material can be found in the DVD's "Making of Willow" documentary. Lucas outlined the "Chronicles of the Shadow War" trilogy to follow the film and hired comic book writer/novelist Chris Claremont to adapt them into a series of books. They take place about fifteen years after the original film and feature the teenage Elora Danan as a central character.