Septimus Pretorius is a fictional character who appears in James Whale's Bride of Frankenstein (1935). He is played by British stage and film actor Ernest Thesiger. Some sources claim he was originally to have been played by Bela Lugosi or Claude Rains. Others indicate that the part was conceived specifically for Thesiger.
Pretorius is the prime villain of the movie, taking on the role of Frankenstein's Monster from the final act of the source novel. Making himself the monster's benefactor, he uses the creature as muscle to force Frankenstein into creating further monsters, which Pretorius claims will usher in a new age of "gods and monsters."
The name Septimus Pretorius is related to the Latin words for Seven and Royal, suggesting the Seven Deadly Sins.