| Pedro de Atarés | |
| Lord of Atarés, Aibar, Javierrelatre and Borja | |
| Noble Family: | Jiménez dynasty |
| Father: | García Sánchez |
| Mother: | Teresa Cajal |
| Death Date: | 21 February 1151 |
| Death Place: | Borja |
| Burial Place: | Veruela Abbey |
Pedro de Atarés (in Borja – 21 February 1151) was a Spanish noble and member of the House of Aragón. He founded the Veruela Abbey, the oldest Cistercian monastery in Aragon.
Pedro de Atarés was the son of García Sánchez, Lord of Aibar, Atarés, and Javierrelatre, and grandson of Sancho Ramírez, Count of Ribagorza, an illegitimate child of King Ramiro I. His mother was Teresa Cajal, a sister of Fortún Garcés Cajal, one of the most powerful magnates in the Kingdom of Aragón.
Pedro inherited the lordships of Atarés and Javierrelatre from his father, and received Borja by gift of King Alfonso VII of Castile, He was one of the claimants to the throne of Aragón after the childless death of King Alfonso I the Battler. According to the Crónica de San Juan de la Peña, written in the 14th century, he had been the preferred candidate of the Aranonese barons but he then alienated them with his haughty behavior at the assembly, and they instead chose the deceased king's brother Ramiro II, until then a monk.
In 1146, Pedro de Atarés founded Veruela Abbey (Real Monasterio de Santa María de Veruela), the most ancient Cistercian monastery in Aragon, with a donation, also confirmed by his mother, to the abbot of the Escaladieu Abbeyin France. This donation was later confirmed in 1155 by Count Raymond Berenguer IV.
Pedro de Atarés died on 21 February 1151 and was buried at the abbey which he had founded. Although he died without leaving any children, members of the House of Borgia invented a genealogy tracing their origins back to this member of the royal house coinciding with the third wedding of Lucrezia Borgia to Alfonso I d'Este, Duke of Ferrara, which was arranged by her father Pope Alexander VI. Nevertheless:
| Candidates for the crowns of Navarre and Aragon in 1134 | ||
| Marriage and legitimate descent | ||
| Liaison and illegitimate descent |