It's funny you brought this topic up now, as two weekends from now will be the 75th anniversary of H.P. Lovecraft's death. We are hving people over to celebrate his works, plyaing Mansions of Madness on Friday Night, and Arkham Horror on Sunday, but on Saturday we will have an H.P. Lovecraft FIlm Festival: Currently I have in my collection:
Cthulhu (c2008)- Here's the deal with Cthulhu. Make the Story into a version of The Shadow Over Innsmounth. Then Make the protagonist gay. Then make it into an attempted Art Film. Makke all of these changes for no apparent reason. Then roll them up into a film, and you have Cthulhu. H.P. Lovecraft's From Beyond (1986) - Starring Jeffery Combs. The first two minutes before the title screen shows up is actually the short story; from there on, it is Stuart Gordon's take on it.
H.P. Lovecraft's: The Tomb (2006) - I haven't seen this one yet, but I've heard it's dreadful. The first line of the back of the box seems to bear that out: "In the terrifying vein of Saw and based on a story by the master of outrageous horror, H.P. Lovecraft . . ." Yeah.
H.P. Lovecraft's Reanimator (1985) - The Stuart Gordon Classic, with Jefferey Combs, about Herbert West's obsession with bringing the dead back to life.
The Dunwich Horror - (1970) Starring Dean Stockwell, and Sandra Dee. I can't say it's good exactly, and there are some downright silly parts, and a very 70's vibe to it, but it still has it's own charm to it and does manage to more or less tell the story in it's own way. You can compare it to . . .
The Dunwich Horror - (c2010) The Dunwich Horror starring Dean Stockwell. THis time around though, instead of portraying WIlbur Whatley, he portrays the protagonist, Dr. Henry Armitage. It uses the Story as a starting point, and then complete moves away from it, but I was amused at the dropping of every single lovecraft reference/name/idea they couls shoehorn in. From Innsmouth, to Charles Dexter Ward, to Olaus Wormius, they cram in as many references as possible.
Die Monster, Die! - (1965) Starring Borris Karloff, this is an adaptation of "The Colour out of Space". Not too faithful, but like many movies of this era, has it's own weird sort of charm.
The Curse (c1984) - Starring Wil Wheaton. Another odd rendition of "The Colour out of Space".
The Manitou (c1973) - An adaptation of the Mythos Novel of the same name, this deals with Ithaqua trying to break into our world.
Castle Freak - (c1990) - A version of "The Outsider".
The Resurrected (1991) - Directed by Dan O'bannon (the writer of Alien), and starring Chris Sarandon, this is a pretty decent retelling of the Case of Charles Dexter Ward.
The Haunted Palace (1963) - Starring Vincent Price with Lon Chaney. Despite the Edgar Allen Poe name on the movie (the studio changed the name to capitalize on Roger Corman's Previous Poe Pictures), it is a fun (if very reworked version of "The Case of Charles Dexter Ward".
The Call of Cthulhu (c2006) - The H.P. Lovecraft Historical Society's silent film of "The Call of Cthulhu. Very well done, including a stopmotion Cthulhu. How awesome is that?
Dagon (2001) - I'm currently in the process of writing a review of this one for the Horror Blog, Forcedviewing.com. The story of Dagon only opens this movie; the main plot of the movies is actually of "The Shadow Over Innsmouth", but now set on the cost of Spain.
The Shunned House (2003) - A terrible film, which attempts to combine "The Shunned House", "The Dreams in the WItch House", and "The Music of Erich Zann" into one plot. Terrible acting, amateur camerawork and writing, and a mess of a plot that makes no sense puts the nail in the coffin of this one.
Lifeforce (1985) - Starring Donald Pleaseance, Base don Colin Wilson's Mythos Novel, "The Star Vampires".
H.P. Lovecraft's "Necronomicon" Starring Jeffery Combs, and David Warner. It retells, "The Rats in the Walls", "Cool Air", and "The Whisperer in Darkness", and is bookended by an Indiana Jonesesque H.P. Lovecraft trying to retrieve the Necronomicon from a cult. None of the adaptations are particularly faithful.
Cast a Deadly Spell (c1990) - With David Warner. A film noir story mixed with the Mythos and a little comedy. It was an HBO Orginal movie and may be a bit hard to find.
The Unnamable (c1990) - Another Dreadful Film, which completely foregoes it's namesake. This one also may be a bit hard to find; Ironically, it sequel (The "Unnamable II: The Statement of Randolph Carter") is marignally better, though still hard to find:
The Dreams in the Witch House (2006) - an episode of the Masters of Horror, collection, which were 1 hour horror movies done by famous horror directors for Showtime. A pretty good rendition, this one directed by Stuart Gordon. Pickman's Model (c1975) - The night Gallery Version of Pickman's model is a pretty decent redition of the story, as is . . .
The Return of the Sorcerer (c1975) - Starring Vincent Price and Bill Bixby. The Night Gallery version of the Clark Ashton Smith Mythos story.
There is also the H.P. Lovecraft collection from Lurker FIlms,of which I only have the first volume of this writing, but their short of "Cool Air" is very good.
There are also some films which were influenced by Lovecraft:
The Thing (1980) - Directed by John Carpenter, starring Kurt Russell is based on the Mythos Short Story, "Who Goes There?" a.k.a. "The Thing From Another World". That story was infulenced by "At the Mountains of Madness".
In the Mouth of Madness (1995) Directed by John Carpenter, and starring Sam Neill is Carpenter's homage to H.P. Lovecraft.
Prince of Darkness (1986) - Directed by John Carpenter, starring Donald Pleasance. While not directly Lovecraft related, some people have called it the most Lovecraftian movie ever made. Afew other movies, such as Cthulhu Mansion (a.k.a. Black Magic Mansion), and The Evil Dead / Army of Darkness series, use a passing refence to Lovecraft in them as well. Hope this helps!