A Self-Writing Quill was a type of quill sold at Weasleys' Wizard Wheezes. In 1996, as part of a weekly managers' special at the store, anyone who purchased this product would receive a free copy of The Novel Cyrillic Novel. 
Behind the scenes
- In the film version of Harry Potter and the Prisoner of Azkaban, there is a quill on Cornelius Fudge's desk that writes on its own while he talks to Harry. It's possible that Self-Writing Quills may have also been sold at other places besides Weasleys' Wizard Wheezes.
- Harry Potter and the Prisoner of Azkaban (film) (Possible appearance)
- Harry Potter and the Half-Blood Prince (film) (Mentioned on poster)