The Master Mystery (1918)
Starring: Harry Houdini, Marguerite Marsh, Ruth Stonehouse, Edna Britton, William Pike, and Charles Graham
Directed by: Harry Grossman and Burton L. King
Screenplay by: Arthur B. Reeve and Charles Logue
Summary: Heroic secret service agent Quentin Locke is investigating an international criminal cartel that's trying to suppress scientific progress; it's protected by a threatening robot called Q the Automaton. Locke is also trying to find the antidote to a gas that induces The Madagascar Madness.
Starring: Alfred Abel, Brigitte Helm, Gustav Fröhlich, and Rudolf Klein-Rogge
Directed by: Fritz Lang
Screenplay by: Thea von Harbou, and Fritz Lang (uncredited)
Summary: In 2026, the technocratic city of Metropolis is divided into two classes — the elite and the working class. It is controlled by Joh Fredersen, whose son becomes infatuated with a young woman named Maria. The activist, who cares for the children of working parents, decides to take them to Metropolis and show them how the other half lives. After a series of horrific incidents, the young man's eyes open to the injustices of his father's city. He enlists a roboticist to help him rebel against his father, setting off a series of unprecedented events involving mad scientists, robots, and social unrest.
The Phantom Creeps (1939)
Starring: Béla Lugosi, Dorothy Arnold, and Robert Kent
Directed by: Ford Beebe and Saul A. Goodkind
Screenplay by: George Plympton, Basil Dickey, and Mildred Barish
Summary: After suffering a personal tragedy, Dr. Alex Zorka turns into a mad-scientist with a utility belt and a sack of gadgets and becomes intent on taking over the world. Among his many powerful weapons and dangerous inventions is an 8-foot tall iron monster he calls "his iron man," and robot spiders that can destroy or paralyze their targets.
Notes* Image 1. is sourced from the public domain / Images 2, 3. are Fair Use.