Sir Kay
His earliest appearance is in Chrétien de Troyes' "Erec and Enide"; in that poem he is borrowed by Sir Kay to joust against Erec. Even Gringolet cannot prevent Kay from losing to the protagonist. In the Lancelot-Grail Cycle, Gawain wins Gringolet from the Saxon king Clarion; a different story of the acquisition is given in Wolfram von Eschenbach's "Parzival", where the horse bears the mark of, and comes from the stable of, the Grail castle - part of the gradual displacement of Gawain by Percival and the story of the grail.