Royal Coat of Arms of the Crown of Castile c 15th. The line of Trastámaran royalty in Castile ruled throughout a time period of military struggle with Aragon. Their family was sustained with large amounts of inbreeding, which led to a series of disputed struggles over rightful claims to the Castilian throne. This lineage ultimately ruled in Castile from the rise to power of Henry II in 1369 through the unification of the crowns under Ferdinand and Isabella
Charles V (24 February 1500 — 21 September 1558) Heir of the Habsburgs of Austria, the Valois of Burgundy, the Trastamara of Castile, and the House of Aragon. Son of Philip I of Castile (Philip the Handsome) and Juana of Castile (Joan the Mad of Castile). Maternal grandparents were Ferdinand II of Aragon and Isabella I of Castile. Paternal grandparents were the Holy Roman Emperor Maximilian I and Mary of Burgundy, whose daughter Margaret raised him.
Anne de Mortimer, Countess of Cambridge (27 December 1390 – c. 21 September 1411) was the mother of Richard Plantagenet, 3rd Duke of York, and the grandmother of King Edward IV and King Richard III. In May 1406, Anne married Richard of Conisburgh, the second son of Edmund of Langley, 1st Duke of York and his first wife Infanta Isabel, Anne Mortimer and Richard, Earl of Cambridge, had two sons and a daughter
Isabella I of Castile, mother to Katherine of Aragon and maternal grandmother of Mary I of England. Detail from The Virgin of the Catholic Monarchs by an unknown artist which depicts Ferdinand II of Aragon and Isabella I of Castile.