Dolls are totally creepy, even when they aren’t in a horror movie. And when they are, you’d better watch out…
Books:

Cuckoo Song by Frances Hardinge follows a girl who awakens after an accident to insatiable hunger and her dolls seeming to move on their own.

Revenge of the Dolls by Carol Beach York is hands down the creepiest doll book I ever read. Of course it’s meant for children. A girl who thinks the dolls her aunt makes are creepy and tosses one into the fire, only to have it come back to haunt her.
Movies:

Annabelle (2014) has spawned a whole franchise. Even though this is based on a true story, they changed the doll from an innocent Raggedy Ann doll to this nightmare.

The Boy (2016) is about a family who hires a nanny to look after a doll. This one had a plot twist that came out of nowhere!

Child’s Play (1988) is the original creepy doll movie franchise starter. The best thing about Chucky is how he looked eerily like a “My Buddy” doll, so naturally anyone who was a kid at the time was freaked out.