Gillywater was a wizarding beverage that was presumably made from Gillyweed. Minerva McGonagall and Luna Lovegood ordered glasses at the The Three Broomsticks, and Romilda Vane once tried to convince Harry Potter to drink some that she had spiked with Love Potion. Harry once mentioned that he dislikes Gillywater, although as he was aware that the one he was being offered was spiked with Love Potion, it is unclear if he actually does dislike it, or if it was just an excuse.
- Harry Potter and the Prisoner of Azkaban
- Harry Potter and the Order of the Phoenix
- Harry Potter and the Half-Blood Prince