Walden Media is moving ahead on development of “Rex Libris,” tapping Ben Zazove to adapt the humorous sci-fi graphic novel.Walden acquired feature rights to “Rex” last year, which follows the zombie-slaying adventures of librarian Rex Libris as he protects the books of the Middleton Public Library and guards the world’s literary treasures from a host of supernatural foes. The graphic novel is written and drawn by James Turner, and published quarterly by Slave Labor Graphics. Warner Bros. had announced in 2007 that “Rex Libris” was in development with Mosaic Media producing. Evan Turner and Michael Bostick are handling the project for Walden, with Brent Lilley handling for Slave Labor Graphics. Walden just released the family adventure “Journey 2: The Mysterious Island” through Warner Bros. Zazove wrote “Tooth Fairy 2″ for Walden and Fox Home Entertainment. He’s repped by Kaplan-Perrone.