I was absolutely terrified when I went to see Anastasia in theaters. I was five, and my mother took me to see it. The climax where Rasputin dies was enough to make me scream and say "I never want to see another PG movie again!!!" (This from the girl who took Twister's father-stealing tornado in stride two years prior.)
The part where Rasputin disintegrates into dust prompted an OCD freak-out in me as a little kid.
I had nightmares for MONTHS after watching this movie and had to go see a counselor...
Rasputin trying to make Anya fall off the edge of a bridge into icy water below.
There are parts of this movie this troper still refuses to watch at the age of 20: the opening scene in which Rasputin makes his deal with the devil, and the part at the end when he disintegrates.
Then there's the spin-off movie Bartok The Magnificent. Especially since the main villainess has a potion that turns whoever drinks it into what they were like on the inside, when Ludmilla drinks it she turns into a dragoness of some kind.