Of Dr. Jekyll and Mr. Hyde, which one was cruel and sadistic?

In Robert Louis Stevenson's classic tale, the cruel and sadistic half of the central character is the monstrous Edward Hyde. He is the physical manifestation of the pure, unrestrained evil that dwells within the otherwise respectable Dr. Henry Jekyll. Tormented by his own darker impulses, the brilliant doctor creates a chemical serum to separate his good and evil natures, believing he can indulge his vices without tarnishing his reputation. The experiment works, but it unleashes Hyde, a morally depraved being who represents the worst of humanity.

Throughout the story, Hyde's actions are a litany of wickedness. He tramples a young girl without a hint of remorse and later beats a man to death in a fit of rage. Unlike Jekyll, who is plagued by guilt over these acts, Hyde revels in his own cruelty and violence. He is the embodiment of the primitive, selfish desires that Victorian society demanded its citizens suppress. As the story progresses, the struggle for control intensifies, as the evil Hyde grows stronger and threatens to consume Jekyll's personality entirely.

This dramatic duality has made the story a cinematic staple for over a century, allowing actors to portray a stunning transformation from a sophisticated gentleman into a brutish fiend. One of the most acclaimed portrayals was by Fredric March in the 1931 film adaptation, for which he won an Academy Award for Best Actor. His performance cemented the visual of the monstrous, ape-like Hyde in the public imagination, a stark contrast (Review) to the tormented, well-meaning doctor.