Thats a difficult one as we all have different takes on Cthulhu, the following is a list of ones I have.
Call of Cthulhu Fan made Black and white, Enjoyable but not fantastic
Cthulhu- some good bits but its really a version of Shadow over innsmouth
Dagon- again some good bits another version of shadow over innsmouth
Hp lovecraft collection 1- Cool Air good adaptation other bits are fun
Hp lovecraft collection 2-Rough Magik-Really enjoyed this one but modern setting
Hp lovecraft collection 3-Out of Mind some cool bits
Hp lovecraft collection 5- Thing on the doorstep low budget but suprisingly good
Castle Freak-not lovecraft but uses some ideas from him
The Lurking Fear- straight to video a couple of visual bits
Bleeders- Trys hard but not up to Lovecraft
Re animator series some ideas but barking mad
Dunwich Horror- Mad stuff, very 60s Psychedelic

The Shunned house- badly done italian film actually music of eric zann and dreams of witch house
to be continued