Henry Franklin Winkler (born October 30, 1945) is an American actor, director, producer, and author. Winkler is best known for his role as Fonzie on the 1970s American sitcom Happy Days. "The Fonz," a leather-clad greaser and auto mechanic, started out as a minor character at the show's beginning but had achieved top billing by the time the show ended.

Henry Winkler plays as Keith from Grief (voice) in Monsters at Work.
Henry Winkler is the top #1 member of the cast and appears in 10 episodes.

Bonnie Lynne Hunt (born September 22, 1961) is an American actress, comedian, writer, director, television producer and daytime television host.

Bonnie Hunt plays as Dolly in Monsters at Work.
Bonnie Hunt is the top #2 member of the cast and appears in 10 episodes.

Alanna Ubach (born October 3, 1975) is an American actress and voice actress. She is known for her roles in Legally Blonde as Serena and Meet the Fockers as Isabel Villalobos. She has provided voices for several characters in a number of animated shows, such as Liz Allan in The Spectacular Spider-Man, the title character in El Tigre: The Adventures of Manny Rivera and Lola Boa in Brandy & Mr. Whiskers. She has also written and performed a one-woman show. She played the first female assistant, Josie, in Beakman's World. Ubach was born in Downey, California, the daughter of Sidna and Rodolfo Ubach. Her sister Athena Ubach is a therapist. Her father is of Puerto Rican descent as well as Mexican. Description above from the Wikipedia article Alanna Ubach, licensed under CC-BY-SA, full list of contributors on Wikipedia.

Alanna Ubach plays as Tessa in Monsters at Work.
Alanna Ubach is the top #3 member of the cast and appears in 10 episodes.

John Goodman is an American stage, film and television actor, best known for his role as Dan Conner on the television series Roseanne, and the hugely popular feature film The Big Lebowski.

John Goodman plays as Eli Gemstone in Monsters at Work.
John Goodman is the top #4 member of the cast and appears in 9 episodes.

William Edward "Billy" Crystal (born March 14, 1948) is an American actor, writer, producer, comedian and film director. He gained prominence in the 1970s for playing Jodie Dallas on the ABC sitcom Soap and became a Hollywood film star during the late 1980s and 1990s, appearing in the critical and box office successes When Harry Met Sally... and City Slickers. He has hosted the Academy Awards eight times.

Billy Crystal plays as Self in Monsters at Work.
Billy Crystal is the top #5 member of the cast and appears in 6 episodes.

Ben Feldman (born May 27, 1980) is an American actor. He has done stage acting, including the Broadway play The Graduate along with Alicia Silverstone and Kathleen Turner. He also played a leading character inThe Perfect Man and portrayed Fran Drescher's son on the television series Living with Fran. From 2009 to 2011, he was a regular on the television series Drop Dead Diva in the role of guardian angel Fred. Feldman left the series at the start of the fourth season, although he made occasional appearances. In April 2012, he joined the cast of AMC's Mad Men as a regular, playing the character Michael Ginsberg. In addition to acting, he also has his own wine label, Angelica Cellars.

Ben Feldman plays as Tylor Tuskmon (voice) in Monsters at Work.
Ben Feldman is the top #6 member of the cast and appears in 2 episodes.

Vera Mindy Chokalingam (born June 24, 1979), known professionally as Mindy Kaling, is an American actress, comedian, and writer. She rose to prominence in 2005 for her work on the NBC sitcom The Office, where she portrayed Kelly Kapoor and served as a writer, executive producer, and occasional director throughout most of the series' run. Kaling created, wrote, produced, and starred in the Fox/Hulu sitcom The Mindy Project, which ran for six seasons from 2012 to 2017. Kailing's film career includes voice work in the films Despicable Me (2010), Wreck It Ralph (2012), Inside Out (2015) and starring roles in the fantasy adventure A Wrinkle in Time and heist-comedy Ocean's 8, both 2018. Description above from the Wikipedia article Mindy Kaling, licensed under CC-BY-SA, full list of contributors on Wikipedia.

Mindy Kaling plays as Val Little (voice) in Monsters at Work.
Mindy Kaling is the top #7 member of the cast and appears in 2 episodes.

Lucas Neff (born 1986) is an American actor from Chicago, Illinois. He is best known for his work in the role of James "Jimmy" Chance in the sitcom Raising Hope. Description above from the Wikipedia article Lucas Neff, licensed under CC-BY-SA, full list of contributors on Wikipedia.

Lucas Neff plays as Duncan (voice) in Monsters at Work.
Lucas Neff is the top #8 member of the cast and appears in 2 episodes.