In the Harry Potter book series, Hermione Granger’s Patronus is an otter.
Hermione produces this silvery animal during the Patronus lessons taught by Harry in Harry Potter and the Order of the Phoenix. The otter is a member of the mustelid family and is often associated with intelligence, playfulness, and curiosity, qualities that fit Hermione’s character.
Patronuses are magical guardians created by the Patronus Charm, which requires the caster to focus on a powerful, happy memory. A Patronus can take either a non-corporeal form or a distinct animal form. Hermione’s is corporeal, meaning it can fully manifest as an animal.
Readers sometimes confuse Hermione’s Patronus with those of other major characters. Harry’s is a stag, Ron’s is a Jack Russell terrier, and Severus Snape’s is a doe. Hermione’s otter is also notable because J. K. Rowling has said it is her favorite animal.