Orson Welles

Character: Joseph Balsamo aka Count Cagliostro

Nancy Guild

Character: Marie Antoinette / Lorenza

Akim Tamiroff

Character: Gitano

Frank Latimore

Character: Gilbert de Rezel

Valentina Cortese

Character: Zoraida

Margot Grahame

Character: Mme. du Barry

Stephen Bekassy

Character: Viscount de Montagne

Berry Kroeger

Character: Alexandre Dumas, Sr.

Gregory Gaye

Character: Chambord / Monk (as Gregory Gay)

Raymond Burr

Character: Alexandre Dumas, Jr.

Charles Goldner

Character: Dr. Franz Anton Mesmer

Lee Kresel

Character: King Louis XVI / Innkeeper

Robert Atkins

Character: King Louis XV

Nicholas Bruce

Character: De Remy

Franco Corsaro

Character: Chico

Annielo Mele

Character: Joseph Balsamo as a Child

Ronald Adam

Character: Court President

Bruce Belfrage

Character: Crown Prosecutor

Alexander Danaroff

Character: Dr. Duval / Baron von Minden

Leonardo Scavino

Character: Gaston / Beniamino Balsamo (as Leon Lenoir)

Tamara Shayne

Character: Maria Balsamo

Joop van Hulzen

Character: Minister of Justice

Peter Trent

Character: Dr. Mesmer's Friend

Giuseppe Varni

Character: Boehmer

Tatyana Pavlova

Character: Grieving Mother

Harriet Medin

Character: (uncredited)

Valentino Bruchi

Character: (uncredited)

Ludmilla Dudarova

Character: (uncredited)

Rosina Galli

Character: (uncredited)

Silvana Mangano

Character: (uncredited)

Filippo Minelli

Character: (uncredited)

Michele Sakara

Character: (uncredited)

Nicholas Soussanin

Character: (uncredited)

Milly Vitale

Character: (uncredited)