Armorial of the House of Plantagenet

The House of Plantagenet was the first truly armigerous royal dynasty of England. Their predecessor, Henry I of England, had presented items decorated with a lion heraldic emblem to his son-in-law, Plantagenet founder Geoffrey, Count of Anjou, and his family experimented with different lion-bearing coats until these coalesced during the reign of his grandson, Richard I (1189–1199), into a coat of arms with three lions on a red field, formally Gules, three lions passant guardant or (armed and langued azure), that became the Royal Arms of England, and colloquially those of England itself.

Source: Wikipedia — Armorial of the House of Plantagenet (CC BY-SA 4.0)