The horror genre has been around for such a large part of the history of film that it has historically been developed simultaneously with the medium itself. One of the most consistent and prominent genres, horror produces thousands of new horror films on an annual basis — this month alone sees the release of The Substance, Never Let Go, Speak No Evil, and many others. With so much competition, it's logical for many horror movies to fall out of the collective consciousness, slipping through the cinematic cracks.
From obscure disasters of cinema such as The Theatre Bizarre to severely underappreciated cult classics such as Stir of Echoes, there is no shortage of lesser-known entries throughout the history of the horror genre. However, that doesn't make them any less worthwhile. In fact, many of horror's most underseen efforts are among its most accomplished, to the point of being the closest thing a movie can come to perfection. These underrated horror movies are pretty much perfect and deserve far more attention from fans...
Because OP is lazy
'Southbound' (2015)
'Viy' (1967)
'Lake Mungo' (2008)
'Stir of Echoes' (1999)
'Horror Express' (1972)
'White Zombie' (1932)
'Cronos' (1992)
'From Beyond' (1986)
'Motel Hell' (1980)
'Black Christmas' (1974)
Not lazy, I just don't see the point in posting a list. I thought it was an interesting article and the discussion about the individual films are worth reading.