Horror Firsts!

just some thoughts:

First horror movie: Le Manoir du Diable (1896) du Georges‬‭ Méliès

First feature length horror movie might have been: L'Inferno (1911)

First horror talkie: The Terror (1911), this is a lost film.

First Russian horror movie might have been: Viy (1909), this is a lost film

First Chinese horror movie might have been: Song at Midnight (1937)

Dream Sequence: the first dream sequence might have been A Nightmare (1896) du Georges‬‭ Méliès

The twist end in film was popularized by The Cabinet of Dr. Caligari (1920)

Quicksand was popularized by Lawrence of Arabia (1962)