You've mentioned the fam has regular movie nights, but what are their favorites? Genre and/or one specific title?
On that note, if there's a clash in tastes, how do they decide which one gets watched?
They'd probably have a rotating system for who gets to pick the movie, but Killer and Horror frequently pass on their turns because they don't really care what the film is (Killer because he loves variety and even enjoys watching bad films for the funnies, Horror because he values the time together more than the activity).
The only real rule for movie night is no horror films or anything overly gorey/violent. Dust and Killer watch those separately, as Horror can't handle them.
Dust would very much be a science fiction fanatic, especially if the science fiction is set in space or involves alien lifeforms in any way. His favourite would be tales about seeking out and exploring new planets, with Interstellar and Project Hail Mary being particular favourites of his.
Horror would love films with strong focuses on family and friendships, and the importance of connection with others. Medium/individual genre would be less important to him than that.
I think he would also love Project Hail Mary as well as Wolf Children and The Chronicles of Narnia.
Nightmare would LOVE period pieces/historical dramas as well as documentaries (both history and nature) and musicals. Among those genres, his favourites would be stories that involve romance.
He would find Little Women to be a particularly interesting film given that it spans multiple points during the lives of the characters and for its commentary on familial bonds and womenhood. He would also adore The Tale of Princess Kaguya (the Ghibli film) because he is absolutely a lover of traditional folktales and would be facinated by the artstyle and melancholy ending.
But his favourite films would be Pride and Prejudice and The Sound of Music.
Cross would love romances and fantasy films. He would probably quite like The Princess Bride and Howl's Moving Castle.
He would also have a bit of a soft spot for old black and white films, given that his own universe was nearly entirely black and white. It feels homey. It's a Wonderful Life and Miracle on 34th Street would be must-watches around Giftmas.
Killer would love action films. Give him anything with decent combat and a tense plot, and he's game. He'd have a good time watching any Star Wars/Marvel/DC movie, Hunger Games, etc, but he usually insists on picking new movies and rarely has favourites. What's the point in having access to every movie ever made in the whole multiverse if you're going to watch the SAME THING over and over?
He'd also adore a good comedy.
Error very rarely bothers to join in for movie nights, and usually only does so at Nightmare's behest. But he is in it for the dramas. Anything with a convoluted family or romance drama plotline is his favourite type of film. He isn't one to bother rewatching movies when he could be binge watching new tv episodes, so he doesn't have any particular favourites.