Along with the Simpson family, The Simpsons includes a large array of characters: co-workers, teachers, family friends, extended relatives, townspeople, 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.^[1]

The main episode characters, the Simpson family, are listed first; all other characters are listed in alphabetical order. Only main, supporting, and recurring characters are listed. For other recurring characters, see List of recurring The Simpsons characters.

List indicator(s)

• M A green cell indicates the character has a main role in that season.
• R A red cell indicates the character has a recurring role in that season. ^{[upper-alpha 1]}
• G A light blue cell indicates the character has a guest role in that season.^{[upper-alpha 2]}
•   A light gray cell indicates the character did not appear in that season.
• O A light gray cell, with an 'O', indicates the character appears only in the opening sequence (including the couch gag and title screen).