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)