Abhorsen is a fantasy novel by Australian writer Garth Nix, first published in 2003. It is the final novel in his Abhorsen trilogy and his third book in the currently five book long planned Old Kingdom series (following Sabriel and Lirael).

Abhorsen features Lirael, who is the recently revealed Abhorsen-in-Waiting; Prince Sameth, who is Lirael's new-found nephew and descendant of the Wallmakers; Mogget, a bound servant of the Abhorsen line; and the Disreputable Dog.