Self (archive footage) (1 episode)
Doctor Schaeffer
David Domedion (1 episode)
Slade
6th Supreme Court Justice (1 episode)
6th Supreme Court Justice
Professor Bowen (1 episode)
Dr. Land
Ray Collins
Dr. Shagetz
Josiah Lowe
Jim Wallace
Arnold Edgarton
Carl Webster
Frederick Wellman
Henry Raphael Caine (1 episode)
Walter Cannell (1 episode)
Warden Auerbach
Sam Baldwin
Prospector
Chad Harmon
Highwayman
Top Polk
Charles Van Cleve
Judge James C. Brown
Jimmy Noble
Whittier
Colonel Baseman
Tony Donovan (1 episode)
Bishop John Atwood (1 episode)
Principal Albert Vane (60 episodes)
George Davies (1 episode)
John Noble
Lt. Gen. John Sparrow (1 episode)
Adam 'Mister Doc' Darrow (1 episode)
Admiral Fitch
Sala Post
Ed Lindsay (1 episode)
William L. Morgan
Grant Austen
Dr. Hubert Van Der Mal
Harry Holt (1 episode)
Mr. Fisher
Harry Burleigh
Anton Rojas
Sheriff Ned Logan
J. Fullerton Weldy
as Rodion Pavlov
John W. Rogers
Philip Carleton
Dr. Adam Royston
Dr. Hugo Thornton
Jade Murphy
Mr. Wyndham
Vice-Adm. Thomas L. Semple
Tim Horn
General Waverly
Police Capt. Michaels
John Straley (1 episode)
Jesse Q. Grimm
Justus
Phil Baxter
General William J. Palmer
Dan Jefferson
Sam Quade
Yancy
Captain Garvey
Jeff Hassard
Major / Lieutenant Colonel Harvey Stovall
Cliff Holden, alias William Harrah
Charles Burnett (1 episode)
Ben Willson (1 episode)
Dr. Steve Webster
Grant
Kevin Connors
Sgt. John Patterson
John Masters
Paul Baxter
Rodion Pavlov
Torgut Lane
'Pipestone' Ross
Jim Sawyer
David Gibson
Edward Creighton
Brigham Young
Charlie (uncredited)
Charlie Sears
James 'Capper' Regan
Paul Herrick
Dillman
Fred Stevens
Alan Shaw
Fritz Lind
Bob O'Ryan
Armand Louque
Hap Waller
'Honey' Hogan
Arnold
Adam Larey
Agent Jones
Bill Trask
Trooper Jim Burton
Top Harmon
Thurman
Coach Robbins
Military School Instructor
Deputy (uncredited)
Jim Coakley