The content of this article is derived from notes and drafts of the Harry Potter books/films/games that were cut before being released. As such, the contents of the article may or may not be considered canonical.
Mopsy was an eccentric elderly witch who lived at the edge of Hogsmeade. She was especially fond of dogs, and kept several, much to the chagrin of her neighbours.
Behind the scenes
J. K. Rowling has stated that she initially wished to include a dog-lover in the story to contrast with the cat-loving Arabella Figg. However, Rowling's editor asked her to cut Mopsy out of an early draft of Harry Potter and the Goblet of Fire. Rowling chose to have fugitive Sirius stay inside a cave instead, where he could freely discuss important matters with Harry, Ron, and Hermione without Mopsy's interference.