In Malory, a Knight of the Round Table who attacked Lancelot, who was disguised in Kay’s armor. Raynold and his companions, Gyllymer and Gautere, who had thought that the inferior Kay was their opponent, received the surprise of their lives.
Raynold was later killed fighting Lancelot and his soldiers when Lancelot rescued Guinevere from the stake.
Source
Le Morte Darthur | Sir Thomas Malory, 1469-1470