Griffon Mask—known as Tizoc in English releases—made his debut in Garou: Mark of the Wolves and has since appeared across both the Fatal Fury and The King of Fighters franchises.
He's a legendary wrestler who became hugely popular with younger fans early in his career. Things were looking unstoppable until some mysterious fighter showed up and absolutely demolished him in the ring. Fan Q&As suggest the guy was Gato's father, though it's never been confirmed outright.
That loss pretty much broke him. He spent the next two years hunting for whoever beat him, and by the time Mark of the Wolves rolls around, he's convinced himself he's washed up. Entering The King of Fighters tournament is his attempt to reclaim what he's lost—both his passion for wrestling and his shot at finding that mystery man who derailed his career.
Content compiled by AnimeList.moe from publicly available sources.