What I can recommend is the film "9".
Details
A scientist creates an AI that produces weapon for the military, but goes all Skynet. To save a part of humanity and life together this scientist creates little dolls.
Pretty disturbing (And I only consider 3 movies as such)
Another classic would be "The Boondock Saints" 1+2
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Two irish brothers put down criminals in the name of god. Hilarius, gory and crazy. Both movies are classics
"11:14 (Eleven-fourteen)" is another gem that's worth watching
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The movie shows different persons in different situations. It all plays around 11:14 pm. Each situation at this evening influences all others, but only at the end all puzzle parts make sense.
Sounds boring, but believe me, it's worth watching
When zombies are favourited "Collapse of the dead" is an underestimated movie
Details
A farmer whitnesses a zombie attack and has to defend his wife and himself. He goes to town to scavenge supplies, meets other survivors and has to stand the final attack.
Sounds like the generic B-movie like "[Insert something] of the dead", but the punchline is genius
And as the last mention:A John Carpenter classic. "They live"
Details
Unknown from most humans, aliens took over the world. The protagonist finds sunglasses that lets him see the true world. From this point he fights the invaders.
For gamers: This was also referenced in Saints Row IV. The mission with Keith David and Roddy Piper at the TV studio
That's my list for good, but not so well known movies.
Updated by anonymous