15. Peter Pan
The copyright is available in the United States. However, there is an exception for the United Kingdom, which has a (limited) perpetual copyright, owned by the Great Ormond Street Hospital. This was gifted to them by Barrie himself in his will and confirmed by an Act of Parliament.
Peter Pan has been utilized in many variations—with Disney’s animated Peter Pan being the most iconic out of all of them. Because of this, it’s best to avoid any and all visual similarities and character portrayals found within the animated feature that aren’t evident in the actual original stage play and book written by James M. Barrie.
That said, there is plenty of opportunity to adapt the material to your own original versions of the stories. Hollywood has tried its best to exhaust the property—most recently with the box-office disappointment of the live action origin story Pan.