Ulwyck Uller is a knight from House Uller and the younger brother of Lord Harmen Uller. He is the uncle of Ellaria Sand, the paramour of Prince Oberyn Martell. This makes him the granduncle of the four youngest Sand Snakes: Elia, Obella, Dorea and Loreza.
A Storm of Swords
A Dance with Dragons
Ulwyck is present along with his brother at the feast when Ser Balon Swann arrives in Sunspear to deliver the head of Ser Gregor Clegane. He refuses to drink when Ricasso raises a toast to King Tommen I Baratheon.