Spaceship to the Unknown

Buster Crabbe

Flash Gordon (archive footage)

Jean Rogers

Dale Arden (archive footage)

Frank Shannon

Dr. Hans Zarkov (archive footage)

Charles Middleton

Ming the Merciless (archive footage)

Priscilla Lawson

Princess Aura (archive footage)

Richard Alexander

Prince Barin (archive footage)

Jack 'Tiny' Lipson

King Vultan (archive footage)

James Pierce

Prince Thun (archive footage)

Earl Askam

Officer Torch (archive footage)

Richard Tucker

Prof. Gordon (archive footage)

George Cleveland

Prof. Henson (archive footage)

Lon Poff

The High Priest (archive footage)

Charles McMurphy

Atom Furnace supervisor (archive footage)

Theodore Lorch

Priest #2 (archive footage)

Duke York

(scenes deleted) (archive footage) (as Duke York Jr.)

Lynton Brent

Transcontinental airplane pilot (archive footage) (uncredited)