J.K. Rowling’s Patronus is an otter.
Rowling identified the otter as her Patronus, linking her own symbolic animal with Hermione Granger’s Patronus in the Harry Potter books. A Patronus is a magical guardian summoned through the complex charm Expecto Patronum. It commonly appears as a silver animal and is used to repel Dementors.
The otter has additional significance in Rowling’s fictional design. Hermione’s Patronus is an otter, and Ron Weasley’s is a Jack Russell terrier. Rowling has explained that otters are among her favorite animals, which helped inspire Hermione’s form.
A Patronus is not the same thing as a house animal, a familiar, or an Animagus form. In the story, a Patronus reflects character and can change in unusual circumstances. Rowling’s otter is a biographical association reported by the author, while Hermione’s otter belongs to the fictional world.