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
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
Stand Up Comic
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)