Peter of Coimbra, sometimes known as Peter V of Aragon, was the son of Infante Peter, Duke of Coimbra, who became the fifth Constable of Portugal and third Grand Master of the Order of Saint Benedict of Aviz. The Consell de Cent later granted Peter the Crown of Aragon, which he claimed from 1463 to 1466 in opposition to John II. His status as king of Aragon, however, along with that of John II's other challengers, is disputed.

Dom Peter, Duke of Coimbra, KG, was a Portuguese infante (prince) of the House of Aviz, son of King Dom John I of Portugal and his wife, Philippa of Lancaster, daughter of John of Gaunt. In Portugal, he is known as Infante Dom Pedro das Sete Partidas [do Mundo], "of the Seven Parts [of the World]" because of his travels. Possibly the best-travelled prince of his time, he was regent between 1439 and 1448. He was also 1st Lord of Montemor-o-Velho, Aveiro, Tentúgal, Cernache, Pereira, Condeixa and Lousã.