9. The Wizard of Oz
The original novel was written by L. Frank Baum in 1900, followed by many sequels from him and others. All of its associated characters are available to adapt, but only from material found in the first 16 books of the series (published in 1922 or before).
This is another property that has been widely utilized on all storytelling platforms. A recent television series was canceled. The Sci-Fi Channel offered its own original take just a few years ago. We’ve since seen feature films and even a hit Broadway musical adapted from it. But the original 1939 film remains to be the adaptation that is most revered.
Writers need to be careful to focus solely on the material found in the books. Any reference to characters and visuals from the classic film and any other adaptation since would be liable for copyright and trademark infringement.