A royal bastard is a child of a reigning monarch born out of wedlock. The king might have a child with a mistress, or the legitimacy of a marriage might be questioned for reasons concerning succession.
Henry Fitzroy was the illegitimate son of King Henry VIII by teenage mistress Elizabeth Blount.
Robert, 1st Earl of Gloucester
Robert FitzRoy, 1st Earl of Gloucester was an illegitimate son of King Henry I of England. He was the half-brother of the Empress Matilda, and her chief military supporter during the civil war known as the Anarchy, in which she vied with Stephen of Blois for the throne of England.
Effigy of Robert Consul, St James' Priory, Bristol. 1840 drawing
Robartus Consull et Mabilia uxor eius ("Robert Consul and Mabel his wife"). They are shown holding churches or abbeys which they founded or were benefactors of, including Tewkesbury Abbey. The attributed arms shown quartered on his tabard and below are: Left: Gules, three clarions or (de Clare, Earl of Gloucester); Centre: Gules, three clarions or (de Clare, Earl of Gloucester) impaling Azure, a lion rampant guardant or (FitzHamon); Right: Azure, a lion rampant or.