[W gwalch, hawk; mai/mei, of May (?)/of the plain (?)].
Welsh counterpart or antecedent of Gawain, here a nephew of Arthur. In Culhwch ac Olwen he rides his horse Ceingalad while accompanying the hero. He acts the peacemaker between Tristan and March ap Meirchion. But according to the Welsh Triads he has no links with Arthur at all.
See Rachel Bromwich, Trioedd Ynys Prydain, rev. edn. (Cardiff, 1978), 369–75, 552.