Alec Baldwin as Theodore Templeton (voice)

James Marsden as Tim Templeton (voice)

Amy Sedaris as Tina Templeton (voice)

Ariana Greenblatt as Tabitha Templeton (voice)

Jeff Goldblum as Dr. Armstrong (voice)

Eva Longoria as Carol Templeton (voice)

James McGrath as Wizzie (voice)

Jimmy Kimmel as Ted Templeton (voice)

Lisa Kudrow as Janice Templeton (voice)

Raphael Alejandro as Nathan / Lead Baby Ninja (voice)

Serenity Reign Brown as Meghan (voice)

David Soren as Jimbo (voice)

Nicholas Gist as The Triplets (voice)

James Ryan as Story Bear (Connie) (voice)

David P. Smith as Movie Patron (voice)

Nova Reed as Little Bo Peep Baby (voice)

Molly K. Gray as Creepy Girl (voice)

Ashlyn Lundahl as 'No' Girl (voice)

Dave Needham as Glue Baby (voice)

Tom McGrath as Dr. Tiffany Hamilton (voice)

Reyn Doi as Box Kid (voice)

Collin Erker as Time Out Kid (voice)

Walt Dohrn as Baby Bouncer (voice)

April Lawrence as Acorn Center Computer (voice)

Miles Bakshi as Young Tim Voice-Over (voice)

Kristin Lowe as Pageant Mom 1 (voice)

Marjorie Cohn as Pageant Mom 2 (voice)

Connor Albrecht as Dreidel Kid (voice)