Don Terry

Cmdr. Don Winslow

Claire Dodd

Mercedes Colby

John Litel

Spencer Merlin

Walter Sande

Lt. Red Pennington

Anne Nagel

Misty Gaye

Wade Boteler

Mike Splendor

Ben Taggart

John Blake

John Holland

Paul Barsac

Lane Chandler

Henchman Corley

Ethan Laidlaw

Henchman Spike

Peter Leeds

Seaman Chapman

Robert Barron

Henchman Prindle

Kurt Katch

The Scorpion

Ray Teal

Gang Radioman Barker

Herbert Rawlinson

Admiral Warburton [Ch. 1]

Samuel S. Hinds

The CINCUS [Ch. 1]

Kenneth Harlan

Capt. Holding [Ch. 1]

Arthur Loft

Enemy Sub Capt. Tranker [Ch. 1]

Jerry Mandy

Tangita Jim [Chs. 2, 10]

Paul Bryar

Saboteur Kramer [Chs. 3-4]

Edward Hearn

Lead Henchman at Mill [Ch. 5]

Iron Eyes Cody

Native Henchman at Mill [Ch. 5]

Frank Lackteen

Witch Doctor Koloka [Chs. 6-7]

Jack Rockwell

Henchman Butch [Ch. 8]

Eddie Polo

Taylor's Lab Assistant [Ch. 8]