Three entries with the name Helyas.
Helyas
A knight who was forced to flee Cornwall with his brother, Assar, after their sister was raped by King Mark. They settled on the Island of Two Brothers.
Later, Helyas abducted Assar’s wife and started a war. Assar received the assistance of Tristan, who slew Helyas in single combat.
Source
Prose Tristan | 1230-1240
Helyas
The leader of Claudas’s sixth division.
Helyas
Elais, Ganors, Ysaies
The fourth of the seven kings whom Lancelot saw in his vision.