John C. Reilly
as Dewey Cox

Jenna Fischer
as Darlene Madison

Raymond J. Barry
as Pa Cox

Kristen Wiig
as Edith

Tim Meadows
as Sam

Harold Ramis
as L'Chai'm

Frankie Muniz
as Buddy Holly

Chris Parnell
as Theo

Margo Martindale
as Ma Cox

Matt Besser
as Dave

Nat Faxon
as Awards Show Stage Manager

Conner Rayburn
as Dewey Age 8

Chip Hormess
as Nate Cox

Terrence Beasor
as Country Doctor

Honeyboy Edwards
as Old Bluesman

Gerry Black
as Harmonica Player

Aron Johnson
as Teenage Band

Jack Donovan Saperstein
as Teenage Band

Taylor Hubert
as Teenage Band

Christopher Hurt
as Teenage Band

Matt Price
as MC (Teacher)

John Maynard
as Man at Talent Show

E.J. Callahan
as Second Man at Talent Show

Rance Howard
as Preacher

Craig Robinson
as Bobby Shad

Paul Bates
as Nightclub Manager

Patrick Faucette
as Bad Men Bass Player

Phil Rosenthal
as Mazeltov

Martin Starr
as Schmendrick

Oscar Dillon
as Audience Guy at Nightclub

Jack McBrayer
as DJ

Molly C. Quinn
as Teen with Pinups

John Ennis
as The Big Bopper

Ed Helms
as Stage Manager

Jack White
as Elvis Presley

Angela Little
as Beth Anne

Odette Annable
as Reefer Girl

Tyler Nilson
as Bert

Deanna Brooks
as Hotel Groupie with Dewey

Ian Roberts
as Drug Dealer

Steve Bannos
as Prison Guard

Willow Geer
as Rehab Nurse

David Doty
as Rehab Doctor

Jack Kehler
as Press Conference Reporter

Gerry Bednob
as The Maharishi

David Krumholtz
as Schwartzberg

Tim Bagley
as Engineer

Jane Lynch
as Gail the Television Reporter

Skyler Gisondo
as Dewdrop

Kshitij Pendurkar
as Dewey Rahim

Simon Helberg
as Dreidel L'Chaim

Jacques Slade
as Lil' Nutzzak

Danica Rozelle
as Music Video Girl

Lurie Poston
as Cox Kid

Maggie Mannion
as Cox Kid

Jackson Browne
as Jackson Browne

Jewel
as Jewel

Lyle Lovett
as Lyle Lovett

Stacey Scowley
as Pierced Eyebrow Girl

Ajla Hodžić
as Pierced Lip Girl

Ghostface Killah
as Ghostface Killah

Otis Williams
as The Temptations

Ron Tyson
as The Temptations

Terry Weeks
as The Temptations

Joe Herndon
as The Temptations

Bruce Williamson
as The Temptations

Eddie Vedder
as Eddie Vedder

Jack Black
as Paul McCartney (uncredited)

Paul Rudd
as John Lennon (uncredited)

Justin Long
as George Harrison (uncredited)

Jason Schwartzman
as Ringo Starr (uncredited)

Patrick J. Adams
as The Kid (uncredited)

Clement Blake
as Edith's Father (uncredited)

Patrick Duffy
as Patrick Duffy (uncredited)

Morgan Fairchild
as Morgan Fairchild (uncredited)

Paul Feig
as Different DJ (uncredited)

Amber Hay
as LSD Vision (uncredited)

John Michael Higgins
as Record Producer

Jonah Hill
as Older Nate

Neil Ironfield
as Dewey's Child (uncredited)

Cheryl Ladd
as Cheryl Ladd (uncredited)

Cheryl Tiegs
as Cheryl Tiegs (uncredited)

Serria Tawan
as 70's African American Woman (uncredited)

Rae Sunshine Lee
as Concert attendee

Gregg Lee
as Concert attendee

Adam Herschman
as Jerry Garcia (uncredited)

Debbie Yeh
as Asian Woman 70's (uncredited)