Alphonso, Earl of Chester (24 November 1273-19 August 1284) was the ninth child of Edward I of England and Eleanor of Castile. He was born at Bayonne, in Gascony, and named after his uncle, King Alfonso X of Castile. Alphonso died at Windsor, aged 10, shortly after the birth of his younger brother (later Edward II of England). His death left his brother as the only surviving male heir of Edward I. Alphonso was interred at Westminster Abbey.