Guillén Pérez de Guzmán (
ca. 1180–1233), a member of the House of Guzmán, one of the most aristocratic of the Kingdom of Castile, was the maternal grandfather of Queen
Beatrice of Castile, Queen Consort of
Portugal as the wife of King
Alfonso III. His father was Pedro Rodríguez de Guzmán—killed in the
Battle of Alarcos on July 18, 1195and son of
Rodrigo Muñoz de Guzmán—and Mahalda With his brothers Nuño and Theobald, he fought alongside King Alfonso VIII at the decisive
Battle of Navas de Tolosa in 1212. Even though his kinsmen supported the
Laras during the crisis that ensued after the death of King Alfonso VIII, Guillén, probably because of his marriage to a member of the Girón clan, supported Queen
Berengaria of Castile and her son, the future king
Ferdinand III.