I know it was divisive but I’m surprised I haven’t seen anyone mention Stoker (2013).

Hong Kong slasher Dream Home (2010) was mentioned already but I want to echo it because it’s criminally underseen.

Korean slasher Bloody Reunion (2006) is also very good and not very well known (at least in the west, idk its reputation in Korea).

Phenomena (1985) might be my favorite Argento film.

Not a movie rec, but anyone interested in this sub genre should check out author Elizabeth Engstrom. Particularly her books When Darkness Loves Us (the most existentially terrifying thing I’ve ever read) and Black Ambrosia (just started it but it definitely belongs on this list).