Billy is a monkey who entered the F-Zero tournament to prove that his is the superior species. He was raised in a laboratory where he was taught literacy and communication skills, and is descended from the first monkey who went to space. Billy is an exceptionally skilled pilot and, at age 7 in F-Zero GX, is also the youngest racer in the Grand Prix.
Billy is a monkey from planet Odyapes, and is descended from the first monkey (of his species) to go into space. He was raised in a lab, where he learned to read and communicate. By the age of 6 (middle age for his species, who only live to be about 16), he had been provided with a vehicle and was racing in the F-Zero Grand Prix. He became popular amongst the other racers for his playful nature, and befriended many of them. He longs to prove that monkeys are a superior race, and has great enough racing skills to do just that. In F-Zero GX, he seemed somewhat obsessed with money.
Billy's vehicle, the Mad Wolf, was built by the same laboratory that raised him. It is a balanced machine with fairly poor grip.