"If someone uses a good move on me I'll be one step ahead the next time he tries it on. And I might use that move on the next person I play." -Dennis "Thresh" Fong interview by Mark Green, Arcade magazine, December 1998, courtesy of Archive.org.
It has been suggested that this is the head of one of the co-founders of id Software, either John Romero or John Carmack, depending on the source. John Carmack and John Romero were both instrumental in the development of Quake II. John Romero generally affected long, dark hair and since the head has short sandy-colored hair this suggests that it is John Carmack.