Cotterpin Doozer is a young female Doozer and the most frequently seen Doozer character in Fraggle Rock. Unlike other Doozers, her passions lie in the realm of art and other "fun" activities as opposed to pure work. Cotterpin is the daughter of Flange Doozer and Wingnut Doozer, and her best friend is Wrench. Though creative, Cotterpin also tends to be stubborn and rebellious.
Though first glimpsed as Wingnut's unnamed infant in "The Great Radish Famine," Cotterpin made her debut as a fully realized character in "All Work and All Play." In that episode, Cotterpin rejected the pressure placed on her to take the helmet, and ran away to become a Fraggle. Cotterpin met and befriended Red Fraggle at this time, though Cotterpin finally realized that she couldn't become a Fraggle. However, Architect Doozer understood her plight and allowed her to "take the drawing board" rather than the helmet.
Cotterpin returned in subsequent episodes, continuing her relationship with Red and forming a close bond, and gradually befriending the other principal Fraggles. This development led to "The Trial of Cotterpin Doozer," in which Cotterpin had to prove that Fraggles were noble and intelligent or else lose her apprenticeship.