"I knew you can do it. I knew you can do it. Yeah."
Billy Matthews

Billy Matthews is a young boy who has autism, but he is very good at basketball, and he easily beats Riley Freeman and the Timid Deer Ball-A-Holics in the climactic match. He only appears in "Ballin'".

Though he's not really an antagonist, he ironically stole Riley's dreams of basketball fame, and he even has a movie made about him starring Haley Joel Osment.