Ulesgalerons, Ylesgaleron, Yllesgalleron
A prince of Wales who joined Arthur’s battle against the Saxons at Vambieres. He is found exclusively in the Livre d’Artus.
His cousin, Guinganbresil, was an enemy of Gawain. When Illesgaleron did not show sufficient hatred for Gawain, Guinganbresil turned on him. His other cousins were Li Giromelans (Guiromelant), Greoreas le Rous and Brandeliz.
There is a twelfth-century non-Arthurian French romance called Illes et Galeron.
Source
Le Livre d’Artus | Early 13th century