Duncan, otherwise known as his nickname Furious D was a racehorse. Bart rescued him from a fair, where he was forced to jump off a diving board. He became a very successful racehorse at the Springfield Downs. After winning the race, he became a stud and lived with a female horse.
Behind the Laughter
Duncan's vocal effects were provided by Jim Cummings. His nickname, “Furious D”, is a reference to the rock band Tenacious D.