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 Cyrillic Model. 
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.
- In the novel Harry Potter and the Deathly Hallows there is a wizard who is murmuring to a quill beside him that writes on its own. This is possibly a Self-Writing Quill or a Quick-Quotes Quill.
- Harry Potter and the Prisoner of Azkaban (film) (Possible appearance)
- Harry Potter and the Half-Blood Prince (film) (Mentioned on poster)
- Harry Potter and the Deathly Hallows (Possible appearance)