Joan of Acre was an English princess, a daughter of Edward I of England and Eleanor of Castile. The name "Acre" derives from her birthplace in the Holy Land while her parents were on a crusade.

Eleanor of Castile was Queen of England as the first wife of Edward I. She was educated at the Castilian court and also ruled as Countess of Ponthieu in her own right from 1279. After diplomatic efforts to secure her marriage and affirm English sovereignty over Gascony, 13-year-old Eleanor was married to Edward at the monastery of Las Huelgas, Burgos, on 1 November 1254. She is believed to have birthed a child not long after.