Inês de Castro (Portuguese pronunciation: [iˈneʒ ðɨ ˈkaʃtɾu]; in Castilian: Inés; 1325 – 7 January 1355) was a Galician noblewoman and courtier, best known as lover and posthumously recognized wife of King Pedro I of Portugal.

King Afonso IV of Portugal, Pedro's father, disliked Inês' influence on his son and waited for their mutual infatuation to wear off, but it did not.

Pêro Coelho, Álvaro Gonçalves, and Diogo Lopes Pacheco went to the Monastery of Santa Clara-a-Velha in Coimbra, where Inês was living at the time, and killed her, decapitating her in front of her small children.

During the 1383–85 Crisis of royal succession in Portugal, João das Regras produced evidence that allegedly established that Pope Innocent VI had refused Pedro's request to recognize his marriage to Inês and legitimize his children by her, the elder of whom, John, Duke of Valencia de Campos would have a strong potential claim to the throne of Portugal.

[3] Some sources say that after Pedro became king of Portugal, he had Inês' body exhumed from her grave and forced the entire court to swear allegiance to their new queen: "The king [Pedro] caused the body of his beloved Inês to be disinterred, and placed on a throne, adorned with the diadem and royal robes, and required all the nobility of the kingdom to approach and kiss the hem of her garment, rendering her when dead that homage which she had not received in her life..."[4] Some modern sources characterize the story of Inês' post-mortem coronation as a "legend"[5] and it is most likely a myth, since the story only appeared in 1577 in Jerónimo Bermúdez' play Nise Laureada.

[8] Both tombs are exquisitely sculpted with scenes from their lives and a promise by Pedro that they would be together até ao fim do mundo (until the end of the world).

The Undiscovered Island, a novel in English by Darrell Kastin, features a descendant's version of the events in the tragedy of Inês de Castro and Dom Pedro.

[14] Christopher Bochman, with the Lisbon Youth Orchestra, has produced an opera "Corpo E Alma" (Body and Soul) focusing on Pedro's transition from a sensual to a spiritual love following her death, drawing on various aspects of the tale.