Eleanor was the daughter of nobleman Pedro Núñez de Guzmán and his wife, Beatriz Ponce de León, a great-granddaughter of King Alfonso IX of León. He preferred Eleanor to his wife Maria of Portugal, daughter of Alfonso IV of Portugal, whom he married in 1328.
De de Velasco (1310–1351) was a Castilian noblewoman and long-term mistress to Alfonso XI of Castile. She was the mother of King Henry II of Castile. Her parents married Eleanor off as a young girl to Juan de Velasco.
Eleanor"s husband died in 1328, at twenty years old.
Soon thereafter, in Seville she met King Alfonso XI. He was so impressed by her beauty that he made her his mistress. After Maria"s son and heir, the future Peter of Castile, was born in 1334, Alfonso left Maria and lived with Eleanor instead.
The king ignored his wife"s pleas, and gave Eleanor Huelva, Tordesillas, and Medina-Sidonia in addition to other holdings. He also established Eleanor"s household in Seville where she was allowed to hear political matters.
The court was increasingly troubled by Alfonso"s behavior and as a result, the Pope intervened by forcing Portugal to invade Castile.
Maria had not forgotten the myriad slights that she had endured because of her husband"s love for his mistress. Thirsting for revenge, Maria imprisoned Eleanor, and later ordered the execution of her rival in 1351 in the Arab castle of Abderrahman III of Talavera de la Reina. Eleanor"s death only exacerbated the rift within the royal family.
Eleanor"s son Henry and Maria"s son Peter continued to fight one another for control of Castile.
