The Simpsons is an American animated sitcom that includes six main voice actors and numerous regular cast and recurring guest stars. The principal cast consists of Dan Castellaneta, Julie Kavner, Nancy Cartwright, Yeardley Smith, Hank Azaria and Harry Shearer. Pamela Hayden, Tress MacNeille, Maggie Roswell, Chris Edgerly, Eric Lopez, Alex Désert, Kevin Michael Richardson, Jenny Yokobori, Kimberly D. Brooks, Dawnn Lewis, Tony Rodriguez, Melanie Minichino, Jonathan Lipow, and Grey DeLisle have appeared as supporting cast members, along with former supporting cast members Russi Taylor, Karl Wiedergott, Marcia Mitzman Gaven, Doris Grau, Susan Blu, Jo Ann Harris, and Christopher Collins. Repeat guest cast members include Marcia Wallace, Phil Hartman, Jon Lovitz, Joe Mantegna and Kelsey Grammer. With the exception of "Old Money", episode credits list only the voice actors, and not the characters they voice.

Both Fox and the production crew wanted to keep their identities secret during the early seasons and closed most of the recording sessions while refusing to publish photos of the recording artists. The network eventually revealed which roles each actor performed in the episode "Old Money", because the producers said the voice actors should receive credit for their work. Every main cast member has won an Emmy for Outstanding Voice-Over Performance. Shearer was the last cast member to win, receiving his award in 2014 for the episode "Four Regrettings and a Funeral." Castellaneta and Azaria have won four, while Kavner, Cartwright, Smith, Shearer, Wallace, Grammer, and guest star Jackie Mason have each won one.