Cuellar or Cuéllar is a Spanish surname derived from Cuéllar, a town in the Segovia province of Spain. The name has a number of variations, including "Cuéllar", "de Cuéllar", "Cuellar", "de Cuellar", "Cuello", "de Cuello", "Coello", and "de Coello". The surname first emerged in the Kingdom of Castile during the Middle Ages.