7. Hagrid's Patronus Is A Boarhound
The Theory: Hagrid might be the most lovable character in the Harry Potter universe, partly because of the sympathy he elicits as a result of his limited magical ability.
The half-giant is capable of performing some magic - as seen when he gives Dudley a curly pig's tail - but the full extent of his power was never really explored in the books or the movies, and this, naturally, has led to fans discussing it.
One of the biggest questions permeating these discussions is whether or not Hagrid can cast a Patronus - a bright white spell that conjures an animal to ward off Dementors. Some people think he can, and have even speculated that his Patronus animal would be a boarhound - the same breed as his pet dog, Fang.
The Debunking: Sound theory, until Rowling came along. In 2015, the author took to Twitter and didn't just quell the whispers about Fang being Hagrid's Patronus, but put a definitive full-stop on the idea that Hagrid could even cast the charm in the first place.
Damn, Hagrid really can't catch a break, can he?