Alfonso VIII (November 11, 1155 – October 5, 1214), king of Castile and grandson of Alfonso VII, is a great name in Spanish history, for he led the coalition of Christian princes and foreign crusaders who broke the power of the Almohades at the battle of the Navas de Tolosa in 1212.

His personal history is that of many medieval kings. He succeeded to the throne, in infancy, on the death of his father, Sancho. Though proclaimed king, he was regarded as a mere name by the unruly nobles to whom a minority was convenient. The devotion of a squire of his household, who carried him on the pommel of his saddle to the stronghold of San Esteban de Gormaz , saved him from falling into the hands of the contending factions of Castro and Lara, or of his uncle Ferdinand of León, who claimed the regency.

The loyalty of the town of Ávila protected his youth. He was barely fifteen when he came forth to do a man's work by restoring his kingdom to order. It was only by a surprise that he recovered his capital Toledo from the hands of the Laras. His marriage with Leonora of Aquitaine, daughter of Henry II of England, brought him under the influence of the greatest governing intellect of his time. Alfonso VIII was the founder of the first Spanish university, the studium generale of Palencia, which, however, did not survive him.

During his reign, Castile annexed the province of Logroño.

In 1176, Alfonso married Eleonor Plantagenet, daughter of King Henry II of England and his wife Eleonor of Aquitaine. They had 12 children:

• Berenguela, or Berenguaria, Queen of Castile (1180-1246), married to Conrad of Hohenstaufen, Duke of Swabia, and then to Alfonso IX, King of León; succeeded her brother, Henry I
• Sancho, prince of Castile (1181)
• Sancha, princess of Castile (1182-1184)
• Urraca, princess of Castile (1186-1220), married to Alfonso II of Portugal
• Blanche, a.k.a Blanche of Castile, princess of Castile (1188-1252), married to Louis VIII of France
• Ferdinand, prince of Castile (1189-1211)
• Mafalda, princess of Castile (1191-1204)
• Henry, prince of Castile (1192 - 1190s)
• Constance or Constanza, princess of Castile (1196 - late 1190s)
• Eleonor or Eleanor, princess of Castile (1202-1244), married to James I of Aragon
• Henry I of Castile (1204-1217) succeeded his father.
• Constance or Constanza, princess of Castile (?-1243), abbess of Las Huelgas