In "Harry Potter and the Prisoner of Azkaban," Buckbeak is a hippogriff. A hippogriff is a magical creature with the front half of a large eagle and the hindquarters of a horse, combining two animals that traditional European mythology usually keeps separate.
Hagrid introduces Buckbeak during his first Care of Magical Creatures lesson at Hogwarts. Students are warned to approach respectfully, bow, and wait for the creature to bow back. Harry succeeds and is rewarded with a flight over the Hogwarts grounds. Draco Malfoy ignores the instructions and insults Buckbeak, provoking an attack that leads to the creature’s death sentence.
The execution is ultimately avoided through Harry and Hermione’s use of the Time-Turner. Buckbeak later helps Sirius Black escape and is renamed Witherwings for part of the series. The name hippogriff itself comes from the Italian poet Ludovico Ariosto’s 16th-century epic poem Orlando Furioso, where the creature represents an unusual union of an eagle and a horse.