Repulsion (1965)

Repulsion is a 1965 British psychological horror film directed by Roman Polanski, and starring Catherine Deneuve.
“A sex-repulsed woman who disapproves of her sister’s boyfriend sinks into depression and has horrific visions of rape and violence.” Sounds pretty grim. And it is. This is actually an excellently made film, a real psychological horror, well paced, well acted, fantastically composed. A creepy decent into madness and murder. 2.5.
Wikipedia

Octaman (1971)

Octaman is a 1971 Mexican-American monster film. Some top level B grade stuff.
“A team of scientists, led by Dr. Rick Torres travels to Mexico to research radioactive material in the water. While there, they discover several octopi that appear to have a human mutation and take them back to the lab for more study. Their benign abduction awakens the parent octopus, however, endangering the lives of all the scientists. Octaman, as he is called, employs several predatory methods, including strangulation and hypnosis.”
Octaman itself looks awesomely B-grade, the story isn’t too dire and its just over an hour long, so its slow pace isnt too bad at all. 2 stars.
Wikipedia