In Perlesvaus, a malevolent lord.
He killed King Marin the Jealous and tried to deprive Meliot, Marin’s son, of his lands. He also stole the holy Circle of Gold, which belonged to Perceval. Gawain reclaimed the Circle and killed Nabigan in combat.
Nabigan’s brother, Anurez, later caused trouble for Gawain and Arthur.
Source
Perlesvaus | Early 13th century