Jack Black

JB

Kyle Gass

KG

JR Reed

Lee

Ronnie James Dio

Dio

Paul F. Tompkins

Open Mic Host

Troy Gentile

Lil' JB

Ned Bellamy

Security Guard

Fred Armisen

Security Guard

Kirk Ward

Car Chase Cop / Gang Leader

Amy Poehler

Truck Stop Waitress

Tim Robbins

The Stranger

Dave Grohl

Satan

Ben Stiller

Guitar Center Guy

Lara Everly

Girl

Brittany Eldridge

Girl

Melissa-Anne Davenport

Girl

John Ennis

Gang Member

Vincent Foster

Gang Member

Jay Johnston

Gang Member

Colin Hanks

Drunk Frat Dude

Stephanie Erb

Al's Bar Waitress

Amy Adams

Gorgeous Woman

Milos Milicevic

Tattooed Biker

Molly Bryant

Ecstatic Woman

Michael Rivkin

Poopy Guy

Gregg Turkington

Neil Hamburger

Patrick M. Walsh

Exploding Head Guy

Bevin Kaye

Fainting Woman

Evie Peck

KG's Mother

Mason Knight

Young KG

Erik Walker

Bully

Cynthia Ettinger

Betty Black

Andrew Lewis Caldwell

Billy Black

Laura Milligan

Tarot Card Reader

Jason Segel

Frat Boy #1 (uncredited)

Meat Loaf

Bud Black (uncredited)

John C. Reilly

Sasquatch (uncredited)