Dead of Night (1945) is a film comprised of various horror episodes that has established horror classics such as the ventriloquist's dummy.
Seeing only the ventriloquist episode in Dead of Night, it is definitely disturbing and creepy with the dummy being suggested to move and speak on its own accord with no definite or real explanation. It is this ambiguity and uncertainly that heightens our terror of the ventriloquist doll as we are left guessing the truth of the malevolent horror that occurs.
There's not too much else I can say about the film as I've yet to see it in its entirety. Though its no doubt that this has inspired many other horror films such as Chucky and 1964's Devil Doll which similarly uses a ventriloquist dummy albeit in a less uncanny and more obvious way.
Essentially, the ventriloquist's dummy is definitely a prime example of the uncanny valley, where the whole concept is actually quite disturbing than entertaining. I guess most ventriloquist avoid this problem with less humanoid creatures in favour of a character that captures human characteristics in a positive light.