Jason Segel as Gary

Amy Adams as Mary

Chris Cooper as Tex Richman

Rashida Jones as CDE Executive

Steve Whitmire as Kermit / Beaker / Statler / Rizzo / Link / Newsman (voice)

Peter Linz as Walter (voice)

Eric Jacobson as Miss Piggy / Fozzie / Animal / Sam Eagle / Marvin Suggs (voice)

Dave Goelz as Gonzo / Honeydew / Zoot / Beauregard / Waldorf (voice)

Bill Barretta as Swedish Chef / Rowlf / Teeth / Pepe / Bobo / Muppet Gary (voice)

David Rudman as Scooter / Janice / Miss Poogy / Wayne (voice)

Matt Vogel as Pepper / Camilla / Sweetums / Robot / Deadly / Harry (voice)

Alan Arkin as Tour Guide

Bill Cobbs as Grandfather

Zach Galifianakis as Hobo Joe

Ken Jeong as Punch Teacher Host

Jim Parsons as Human Walter

Eddie Pepitone as Postman

Kristen Schaal as Moderator

Sarah Silverman as Greeter

Eddie 'Piolin' Sotelo as TV Executive

Raymond Ma as Elderly Asian Man

Shu Lan Tuan as Elderly Asian Woman

Donald Glover as Junior CDE Executive

Dahlia Waingort as TV Executive

Jonathan Palmer as Reporter One

Don Yanan as Reporter Two

Michael Albala as TV Executive

Julia Marie Franzese as Punch Teacher Kid

Gunnar Smith as Gary Age 6

Connor Gallagher as Gary Age 9

Justin Marco as Gary Age 13

Cameron Kasal as Laughing Kid

Justin Tinucci as Laughing Kid

Alex Long as Laughing Kid

Aria Noelle Curzon as Waitress

Emily Blunt as Miss Piggy's Receptionist

James Carville as James Carville

Leslie Feist as Smalltown Resident

Whoopi Goldberg as Whoopi Goldberg

Selena Gomez as Selena Gomez

Dave Grohl as Animool

Neil Patrick Harris as Neil Patrick Harris

Judd Hirsch as Judd Hirsch

John Krasinski as John Krasinski

Rico Rodriguez as Rico Rodriguez

Mickey Rooney as Smalltown Resident

Tyler Bunch as Fozzie Moopet / Thog / Additional Muppet Performer (voice)

Bruce Lanoil as Additional Muppet Performer (voice)

Michelan Sisti as Additional Muppet Performer (voice)

Paul McGinnis as Additional Muppet Performer (voice)

Greg Ballora as Additional Muppet Performer (voice)

David Alan Barclay as Additional Muppet Performer (voice)

Tim Blaney as Additional Muppet Performer (voice)

Kevin Carlson as Additional Muppet Performer (voice)

Leslie Carrara-Rudolph as Additional Muppet Performer (voice)

Kristin Charney as Additional Muppet Performer (voice)

Nathan Danforth as Additional Muppet Performer (voice)

Alice Dinnean as Afghan Hound / Wanda / Additional Muppet Performer (voice)

Julia Gunn as Additional Muppet Performer (voice)

BJ Guyer as Additional Muppet Performer (voice)

Tanya Haden as Additional Muppet Performer (voice)

Patrick Johnson as Additional Muppet Performer (voice)

Sean W. Johnson as Additional Muppet Performer (voice)

Len Levitt as Additional Muppet Performer (voice)

James Murray as Additional Muppet Performer (voice)

Michael Oosterom as Additional Muppet Performer (voice)

Karen Prell as Additional Muppet Performer (voice)

Mike Quinn as Additional Muppet Performer (voice)

David Skelly as Additional Muppet Performer (voice)

Andy Stone as Additional Muppet Performer (voice)

Art Vega as Additional Muppet Performer (voice)

Alex Villa as Additional Muppet Performer (voice)

Chase Woolner as Additional Muppet Performer (voice)

Jack Black as Jack Black (uncredited)

Mike Carlucci as Scout Troop Leader (uncredited)

Reese Hartwig as Punch Teacher Contestant (uncredited)

Jerry Nelson as Telethon Announcer (voice) (uncredited)