Spitfire is a Pegasus pony and the captain of the aerial acrobatics group, The Wonderbolts. She makes her debut in Sonic Rainboom, and her name is first used in The Best Night Ever. She and Soarin' are the first two members of The Wonderbolts to be named on the show. Spitfire is a term denoting a person with a fierce temper. The Supermarine Spitfire is also the name of an iconic British-produced Allied fighter aircraft used in the Second World War.