There are a pretty decent lot of films with Lovecraftian themes, all of hugely varying levels of quality. "Lovecraftian" is a phrase that refers to things influenced by the legendary horror writer, since he is known as one of the forefathers of the cosmic horror genre.
His concept of horror included things like madness, family curses, accursed people who might not be what they seem, cults, the things that lurk in the deep of the ocean, and entities that exist in the furthest reaches of space—or perhaps even outside of space and time themselves. The issue with adapting Lovecraft to screen is that sometimes the horrors that Lovecraft writes of are too terrible to be described, let alone captured on film.
Best: The Thing (8.1)
John Carpenter's The Thing might just be one of the best horror movies of all time, not just Lovecraftian films in particular. The film follows a team of scientists who are trapped at a base in Antarctica during a research expedition. When a helicopter crash-lands nearby and people on the team begin to go missing, everyone quickly loses any sense of trust and goes into survival mode. There's an alien monster in the base that can take over the corpses of people it's killed, and it's a fight to identify and eliminate the unknowable horror before it's too late.
Worst: Alone In The Dark (2.4)
Featuring Christian Slater as one of the staple character types of any Lovecraftian horror, Alone In The Dark follows a paranormal investigator named Edward Carnby who is pitted against an ancient cult that's attempting to bring about their version of hell on earth. He's fraught with psychological trauma for most of the film, as the evils surrounding him do their best to whittle away at what little sanity he has left.
Best: Dark City (7.6)
Dark City is a very interesting film that's nothing if not Lovecraftian, although it contains some notes of a horror version of Oldboy or something like that. We follow our protagonist, John Murdoch, who knows no more about himself than we do.
He's lost his memory and is wanted for several murders that have been orchestrated by a mysterious group of creatures called The Strangers, who have the ability to erase memories and put people to sleep at their whim.
Worst: The Dooms Chapel Horror (3.5)
The Dooms Chapel Horror harkens to the title of a Lovecraft story entitled The Dunwich Horror, but there's really no relation between the two. Instead, we follow Kyle Cole, a man who was somehow framed for the murder of his brother, who was somewhat of a Laura Palmer from Twin Peaks type who was nearly perfect and could do no wrong. The movie doesn't exactly flow very well and can be hard to follow, but there's at least some payoff.
Best: The Lighthouse (7.5)
The Lighthouse is the second film to be released by Robert Eggers, who's also pretty well-known for his slow-burn middle America fairytale taking place in colonial times called The Witch. This film is notably more Lovecraftian, but not in the way all the tentacles in the trailer would have you expect. As tensions mount between two stranded lighthouse keepers, neither the characters nor the viewer has any clue what's real anymore as they quickly lose touch.
Worst: The Haunter Of The Dark II (3.6)
This movie feels like the plot is really heavily related to something like Alan Wake, a horror game with very heavy Lovecraftian elements.
The film is about a writer who has dreams of a town called Providensk, which is probably a reference to Providence, Rhode Island, a city in which H.P. Lovecraft spent a very significant portion of his life. He decides to head for the town for better or worse, and, as the movie goes on, we find out that it's definitely for worse.
Best: The Mist (7.1)
The Mist is a film that's based on a Stephen King story rather than a Lovecraft story, but that's perfectly alright, as King is perfectly upfront about being majorly influenced by the author. In fact, their settings are often remarkably similar as a result of both coming from New England.
The film tells the story of a mist that rolls into a small town, carrying with it a group of unseen bloodthirsty creatures. As townsfolk all take refuge in a grocery, which quickly runs out of supplies, things quickly devolve into a tense fight for survival that doesn't end well for anyone.
Worst: The Barge People (4.0)
The Barge People couldn't be more upfront about the influence it takes from Lovecraft if it tried, and maybe that's what ends up hurting it.
The film tells the story of two sisters and their significant others who go on a vacation in Britain, only to realize that their perfect destination isn't as it seems. It's filled with bloodthirsty fish people. This exact plotline happens in one of Lovecraft's more famous tales, The Shadow Over Innsmouth, but it lacks much of the nuance and subtle terror that made Lovecraft's work so notorious.
Best: The Cabin In The Woods (7.0)
The Cabin In The Woods is a film that seems at first just to be a silly little satire about slashers, maybe even one that's not quite as smart as it thinks it is. However, that couldn't be further from the truth; the film takes place among a group of friends who're on a camping trip, which is a familiar enough plot. They then have various horror movie monsters unleashed upon them. We find out the ones orchestrating it aren't evil but trying to save the planet from an even bigger, far more Lovecraftian threat.
Worst: Dark Heritage (4.2)
This film is through-and-through Lovecraftian, all the way through to the fact that the movie checks the boxes of the old American town, the reporter who goes to check out some strange happenings, and the weird family cult thing that Lovecraft always had going on. The film is actually an adaptation of a story by Lovecraft called The Lurking Fear, although it was neither marketed nor released that way.