Michael Keaton
Johnny Dangerously

Joe Piscopo
Vermin

Marilu Henner
Lil

Maureen Stapleton
Mom

Peter Boyle
Dundee

Griffin Dunne
Tommy

Glynnis O'Connor
Sally

Dom DeLuise
The Pope

Richard Dimitri
Maroni

Danny DeVito
Burr

Ron Carey
Pat

Ray Walston
Vendor

Dick Butkus
Arthur

Byron Thames
Young Johnny

Sudie Bond
Cleaning Lady

Alan Hale Jr.
Desk Sergeant

Scott Thomson
Charley

Carl Gottlieb
Dr. Magnus

Neal Israel
Dr. Zillman

Mike Bacarella
Vito

Hank Garrett
Mayor

Leonard Termo
Tony Scarano

Troy Slaten
Young Tommy

Cynthia Szigeti
Mrs. Capone

Elizabeth Arlen
Girl on Steps

Richard Warwick
Prisoner

Will Seltzer
Prisoner

Dick Balduzzi
Prisoner

Frank Slaten
Henchman

Jack Nance
Priest

Rick Rosenthal
Judge

Harvey Parry
Policeman

Jeffrey Weissman
T-Shirt Vendor

Chuck Hicks
Governor

Bob Eubanks
M.C.

Vincent Schiavelli
Maroni's Building Planner (uncredited)

Taylor Negron
Delivery Man (uncredited)

Joe Flaherty
Death Row Inmate (uncredited)

Hank Robinson
Policeman (uncredited)

Susan Lanier
Radio Singer (uncredited)

Frank Sivero
Plumber (uncredited)

Tom Willett
Theater Patron (uncredited)