Dr. Septimus Pretorius is the main antagonist of the monster film Bride of Frankenstein. Pretorius is depicted as a mad scientist who asks Dr. Frankenstein to help him create a woman from dead human tissue and he convinces him by menacing him with the monster that Frankenstein himself created. When the bride finally lives she is scared by the sight of Frankenstein's monster.

The monster gets angry and tears castle Frankenstein to pieces by letting it explode thus killing himself, the bride and Dr. Pretorius, while Dr Frankenstein escapes as the monster spares him his life.

He was played by Ernest Thesiger.