Spencer Tracy as Thomas A. Edison

Charles Coburn as General Powell

Lynne Overman as Bunt Cavatt

Rita Johnson as Mary Stilwell

Gene Lockhart as Mr. Taggart

Henry Travers as Ben Els

Felix Bressart as Michael Simon

Peter Godfrey as Ashton

Guy D'Ennery as Lundstrom

Byron Foulger as Edwin Hall

Milton Parsons as 'Acid' Graham

Arthur Aylesworth as Bigelow

Gene Reynolds as Jimmy Price

Addison Richards as Mr. Johnson

Grant Mitchell as Snade

Paul Hurst as Sheriff

George Lessey as Toastmaster

Jay Ward as John Schofield

Ann Gillis as Nancy Grey

Erville Alderson as First Lecturer

William Arnold as Minor Role

Hooper Atchley as Broker

Irving Bacon as Sheriff

Arthur Belasco as Broker

Edward Biby as Party Guest

Billy Bletcher as Reporter

Harry C. Bradley as Preacher

Harlan Briggs as Bisbee

Fritzi Brunette as Minor Role

John Butler as Mechanic

James Carlisle as Party Guest

George Chandler as Gold Exchange Clerk

Howard Chase as Minor Role

James Conaty as Party Guest

Jimmy Conlin as Waiter

Nick Copeland as Reporter

Maurice Costello as Broker

Nell Craig as Woman

Jack Daley as Minor Role

Edgar Dearing as Policeman

Helen Dickson as Minor Role

John Dilson as Broker

Donald Douglas as Jordan

Edward Earle as Broker

Frank Faylen as Galbreath

Walter Fenner as Man at Banquet

Eddie Gribbon as Cashier

Hale Hamilton as Broker

Sam Harris as Party Guest

Edward Hearn as Broker

Arthur Stuart Hull as Broker

Harry Humphrey as Broker

Edward Keane as Lecturer

Eve Kendall as Marion Estelle Edison

Milton Kibbee as Workman

Charles Lane as Second Lecturer

Edward LeSaint as Doctor

Wilfred Lucas as Broker

Tom Mahoney as Policeman

Eric Mayne as Party Guest

Ralph McCullough as Reporter

George Meader as Minister

Harold Minjir as Blair

Bruce Mitchell as Coachman

Hans Moebus as Party Guest

Edmund Mortimer as Party Guest

Forbes Murray as Broker

Louis Natheaux as Broker

Alex Novinsky as Party Guest

William H. O'Brien as Waiter

George Ovey as Lamplighter

Thomas Pogue as Minor Role

Alexander Pollard as Butler

Cyril Ring as Reporter

Count Stefenelli as Party Guest

Harry Strang as Minor Role

Charles Trowbridge as Clark

Emmett Vogan as Secretary

Charles Waldron as First Commissioner

Frank Whitbeck as Trailer Narrator (voice)

Joe Whitehead as Minor Role

Lloyd Whitlock as Broker

Robert Winkler as Newsboy