Isabel Enríquez de Castilla

Isabel Enríquez (died 1420/1) was a member of the Castilian royal family and a Poor Clare. She was an illegitimate daughter of King Henry II of Castile and an unknown woman.

She married Gonzalo Núñez de Guzmán in secret. For this, Gonzalo was excommunicated and imprisoned. It has been suggested that Gonzalo may have kidnapped Isabel, on the grounds that a merely secret marriage would not have incurred either prison or excommunication. In any case, Gonzalo later entered the Order of Alcántara, rising to become master in 1384. His excommunication was only lifted by Archbishop Pedro Tenorio on 23 September 1395.

Isabel and Gonzalo are usually assumed to have had no children, although Luis González de Guzmán may have been their son.

By 1387, Isabel had entered the convent of Santa Clara la Real de Toledo. In 1393, her sister was elected abbess and Isabel acted as de facto co-abbess with her. Their presence attracted royal largesse. Both Henry III and, after the sisters' deaths, John II, made donations to Santa Clara because of their "aunts, abbesses" . A contemporary painting of the sisters can be seen on the wall of the choir.

She died at Santa Clara in 1420 or 1421.