Along with the Simpson family, The Simpsons includes a large array of characters: co-workers, teachers, family friends, extended relatives, townspeople, as well as local celebrities. The creators originally intended many of these characters as one-time jokesters or for fulfilling needed functions in the town. A number of them have gained expanded roles and subsequently starred in their own episodes. According to creator Matt Groening, the show adopted the concept of a large supporting cast from the Canadian sketch comedy show Second City Television.