Devil Doll(1964) -

The film’s most unsettling element is the dummy, Hugo. While most ventriloquist films play with the ambiguity of whether the doll is "alive" or merely an expression of the handler’s fractured mind, Devil Doll leanings into the supernatural early on. It is eventually revealed that Hugo is not just a doll, but a vessel containing the soul of Vorelli's former partner, whom he murdered and imprisoned.

: By making the ventriloquist a conscious villain rather than a mental patient, the film shifts the horror from internal madness to external exploitation. Devil Doll(1964)

At the heart of the film is the malevolent hypnotist and ventriloquist, The Great Vorelli (played with sinister intensity by Bryant Haliday). Unlike many ventriloquist characters who are victims of their own psychosis, Vorelli is a calculating predator. He uses his stage act as a front for genuine occult practices, employing telepathic powers to ensnare his victims—most notably the young heiress Marianne Horn. The film’s most unsettling element is the dummy, Hugo

Compare its themes to the (which has a completely different plot). List other classic "creepy dummy" movies from that era. : By making the ventriloquist a conscious villain