Deposed by Henry of Trastámara (Henry II of Castile)
House of Burgundy
"Popular memory generally views Peter as a vicious monster. Much but not all of Peter's reputation comes from the works of the chronicler Pero López de Ayala, who after his father's change of allegiance had little choice but to serve Peter's usurper. After time passed, there was a reaction in Peter's favour and an alternative name was found for him. It became a fashion to speak of him as El Justiciero, the executor of justice (the Lawful). Apologists were found to say that he had killed only men who would not submit themselves to the law or respect the rights of others." 
Nicknamed: ES: Pedro el Cruel; EN: Peter the Cruel
Peter's children by María de Padilla were:
Beatrice (1353–1369), nun at the Abbey of Santa Clara at Tordesillas
Constance (1354–1394), married John of Gaunt, 1st Duke of Lancaster
Isabella (1355–1392), married Edmund of Langley, 1st Duke of York
Alfonso (1359–1362), Crown Prince of Castile and León (Tordesillas, 1359 – 19 October 1362). Peter forced the Cortes to recognize Alfonso as his legitimate heir on 29 April 1362. However, Alfonso, a very sickly child, died at the age of three, months from his recognition as Crown Prince.
Peter had one son with Juana de Castro, daughter of Pedro Fernández de Castro:
John (1355–1405), married doña Elvira de Eril, had issue:
Pedro (died 1461) bishop of Osma and Palencia.
Peter had a daughter with Teresa de Ayala, a niece of Pero Lopez de Ayala:
Maria de Ayala, who with her mother had long careers at the Dominican convent of Santo Domingo el Real in Toledo and maintained a friendly correspondence with the Trastámaras
Peter had a son with Isabel de Sandoval:
Diego de Castilla, married Isabel de Salasar;
Pedro "el Viejo" de Castilla, married Beatriz de Fonseca y Ulloa;
Pedro "el Mozo" de Castilla, who had two illegitimate sons by Joanna of Portugal
Pedro I de Castilla, nacido en Burgos, Castilla, 30 de agosto de 1334, llamado el Cruel por sus detractores y el Justiciero por sus partidarios, fue rey de Castilla desde el 26 de marzo de 1350.
Called Peter the Cruel or Peter the Just. He married and caused to be murdered Blanche de Bourbon and later Juana de Castro, whom he deserted after she bore him a son. Maria de Padilla was his mistress; they were married in 1353.
His parents were double first cousins.
Royal Ancestry by Douglas Richardson Vol. II page 121-122