Gwalchmei is a great Arthurian hero in Welsh tradition.
He is, in extant texts, identical to the Gawain of French romances, but the name Gwalchmei cannot be equated with Gawain by etymological methods.
This might not matter, as names sometimes are not translated properly across a language. For example, in Germanic tales, the Norse Sigurð and the southern Siegfried are obviously the same person, but their names are not identical. Sigurð is deemed to derive from an postulated form *Sigiwarð which would be cognate to Old English Sigeweard, later Siward, whereas Siegfried (Sîfrit) corresponds to Old English Sigefrið. The name of this hero’s wife is even more discrepant: in the north she is Gudrun and in the south she is Kriemhild.
Still, despite such examples, some think that Gwalchmei was in origin entirely separate from Gawain, but was equated with him, just as the Welsh also equated a hero named Peredur with the French Perceval, equated their Gereint son of Erbin with the French Erec son of Lac, and equated Cynon son of Clydno with the French Calogrenant.
Gwalch means ‘hawk’. Gwalchmei might mean ‘Hawk of May’ or ‘Hawk of the Plain’ or even something like ‘Hawk-beak’.
In the Stanzas of the Graves it is told: “Gwalchmei’s grave is in Peryton”. Peryton could be Peryddon which is a tributary of the River Mennow in Monmouth but it is also found as a name for the River Dee.
From the Welsh tale Culhwch and Olwen (as translated by Lady Charlotte Guest):
He [Arthur] called Gwalchmei son of Gwyar, because he never returned home without achieving the adventure on which he went in quest. He was the best of footmen and the best of knights. He was nephew to Arthur, the son of his sister, and his cousin.
A variant version of Bromwich’s Welsh Triad 42 reads “Kein Caled, the horse of Gwalchmei”. The name Keincaled is obviously related to Gringalet, the name of Gawain’s horse in various non-Welsh romances.
From the Welsh tale Gereint (as translated by Lady Charlotte Guest):
And thus were they appointed: one church for Arthur, and his Kings, and his guests; and the second for Gwenhwyvar and her ladies; and the third for the Steward of the Household and the suitors; and the fourth for the Franks and the other officers; and the other nine churches were for the nine Masters of the Household and chiefly for Gwalchmei; for he, from the eminence of his warlike fame, and from the nobleness of his birth, was the most exalted of the nine.
In the Welsh tale The Lady of the Fountain, Owein battles Gwalchmei before the fountain, neither knowing the other until Owein knocks Gwalchmei’s helmet askew and recognizes him. Owein at once says, “I did not know you for my cousin.” But in Chrétien de Troyes’ Yvain there is no suggestion that Yvain and Gawain are related. The author may be relying on the writing of Geoffrey of Monmouth (and Welsh adaptations thereof) which indicates that the fathers of the two knights were brothers.