In “House of the Dragon,” several characters become dragon riders during the Dance of Dragons:

Hugh Hammer: He is a blacksmith who discovers he has Targaryen blood and becomes a dragon rider. He mounts Vermithor, the second-largest dragon in Westeros, and fights for the Blacks.

Ulf White: He claims to be the bastard son of Baelor the Brave and the grandson of King Jaehaerys I. He aligns with the Blacks and becomes a dragon rider.

Addam of Hull: He is the illegitimate son of Lord Corlys Velaryon and Marilda of Hull. Addam becomes the rider of Seasmoke, a silver-gray dragon that had previously been ridden by Laenor Velaryon.