Nathan Lane

Spot Helperman / Scott Leadready II / Scott Manly-Manning (voice)

Kelsey Grammer

Dr. Ivan Krank (voice)

Shaun Fleming

Leonard Amadeus Helperman (voice)

Debra Jo Rupp

Mrs. Mary Lou Moira Angela Darling Helperman (voice)

David Ogden Stiers

Mr. Jolly (voice)

Jerry Stiller

Pretty Boy (voice)

Paul Reubens

Dennis (voice)

Megan Mullally

Adele (voice)

Wallace Shawn

Principal Crosby Strickler (voice)

Rob Paulsen

Ian Wazselewski (voice)

Jay Thomas

Barry Anger (voice)

Estelle Harris

Mrs. Boogin (voice)