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'Chaim

Margo Martindale as Ma Cox

Chris Parnell as Theo

Matt Besser as Dave

Nat Faxon as Awards Show Stage Manager

Conner Rayburn as Dewey Age 8

Chip Hormess as Nate

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

Frankie Muniz as Buddy Holly

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 (uncredited)

Jonah Hill as Older Nate (uncredited)

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)

Adam Herschman as Jerry Garcia (uncredited)

John D. Crawford as Officer Clark