The antagonist in Rumble Fish by S. E. Hinton is Biff Wilcox. Biff threatens Rusty-James because he talked to Anita. Instead of trying to resolve the misunderstanding in a humane manner, Biff tells Rusty that he will kill him. On the night of the fight, Biff removes a knife and attempts to injure Rusty who did not carry any weapon. Therefore, Biff fights unfairly, however, Rusty manages to disarm him and single-handedly wins the fight. After the fight, Motorcycle Boy appears and distracts Rusty. Biff takes advantage of Rusty being distracted by picking up the knife and stabbing him. Biff Wilcox shows no remorse towards Rusty and gloats at him because he is injured. Motorcycle Boy then hits Biff with his bike to save his brother.

Biff Wilcox "is a member of another group, formerly allies of Rusty-James's group, now enemies. Rusty-James notes that if the old gang wars were still going on, Biff would be leader of his gang, the Devilhawks. He is tougher and more dangerous than most kids." However, the real antagonist in this novel is poverty.  Rusty, Motorcycle Boy, Biff, these kids are never going to get away from their dead end lives because the poverty of life is like an anchor around their souls.