Gillomaurus, Gillomanius, Gillomen, Guillomer
Gilloman heard that Uther and Merlin had landed in Ireland to take away the Giants’ Dance (Stonehenge) from Mount Killaraus. Enraged, Gilloman assembled his soldiers and attacked Uther’s party as they headed toward the Mount Killaraus, but Uther was victorious.
Gilloman later allied with Vortigern’s son, Pascentius, in an attempt to conquer Britain from Ambrosius. They met Uther at Saint David’s (or at Menevia) in Wales, and both Gilloman and Pascentius were killed in the battle.
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138