Guinebant, Guinebas, Guinebaus, Guinebaut
The brother of Kings Ban and Bors, Gwenbaus accompanied them to England when they came as Arthur’s allies during the early war against the rebel kings.
Malory characterizes Gwenbaus simply as “a wise clerk”. From the Vulgate we learn that he was a clerk of necromancy and did a bit of hobnobbing with Merlin.
Gwenbaus met, loved, and remained with a king’s daughter in the Forest Perilous in England until his and her deaths (apparently natural).
Source
Le Morte Darthur | Sir Thomas Malory, 1469-1470