Trevor is the name of Neville Longbottom’s pet toad in the Harry Potter books.
Neville brings Trevor to Hogwarts and repeatedly worries that the toad may escape. Trevor is mentioned early in Harry Potter and the Philosopher’s Stone, when Neville searches for him before the students travel to Hogwarts. The missing-toad storyline helps introduce Neville as a nervous but kind-hearted first-year student.
Trevor is a toad rather than an owl, cat, or rat. Harry owns an owl named Hedwig, Hermione owns a cat named Crookshanks, and Ron initially keeps a rat named Scabbers. These pets are often confused because they appear around the same group of students, but each belongs to a different character.
Neville’s relationship with Trevor is also a small recurring joke: Trevor frequently gets loose, and Neville’s grandmother originally gave him the toad. As Neville grows more confident, Trevor becomes less important to the plot, while Neville himself develops into a major member of the resistance against Voldemort.