Urraca of Castile (1082 – March 8, 1126) was Queen of Castile and León from 1109 to her death. She was the daughter of Alfonso VI of Castile by his second wife, Constance of Burgundy. She became heiress to her father's kingdom after her only brother was killed at the battle of Ucles in 1108.

She had been married as a child to Raymond of Burgundy, who died in September 1107. They had two small children: Infante Alfonso Raimúndez (born 1104) and the Infanta Sancha (born before 1095). Now a widow, Urraca was ruler of Galicia. She was also her father's only surviving legitimate child, and now the heiress to Castile. King Alfonso VI selected a new husband for her, and his choice fell on Alfonso I of Aragon, who he hoped would safeguard the kingdom. Urraca and Alfonso of Aragon were related within forbidden degrees, and Bernard, Archbishop of Toledo, objected to the marriage on these grounds. Nevertheless, Urraca and Alfonso were married in October 1109 at Monzón. The marriage was condemned as consanguinous.

Alfonso was renowned as a great warrior; according to the chronicler Ibn al-Athir, he once remarked that a real soldier lives with men, not with women. Urraca accused him of being physically abusive to her, and their inability to produce a child created a further rift between them. She took a lover, Count Gómez González, and the royal couple were separated by 1111.

Her reign was disturbed by strife among the powerful nobles and especially by constant warfare with her husband, who had seized her lands. Their marriage was annulled in 1114, and Urraca never remarried, though she took several lovers. Another thorn in her side was her brother-in-law Henry, the husband of her half-sister Teresa of Leon. He alternatively allied with Alfonso I of Aragon, then betrayed Alfonso a better offer came from Urraca's court. After his death in 1112 his widow Teresa still contested ownership of lands with Urraca. With the aid of her son, Alfonso Raimúndez, Urraca was able to win back much of her domain and ruled successfully for many years.

According to the Chronicon Compostellanum, Urraca died in childbirth in 1126. The father was her lover, Count Pedro González of Lara. She was succeeded by her legitimate son, Alfonso VII.

Illegitimate children
Besides her two legitimate children by Raymond of Burgundy, Urraca also had an illegitimate son by her lover, Pedro González de Lara. She recognized their son, Fernando Perez Furtado, in 1123.