Ooh, my kids are heading deep into teenager territory so this feels like my chosen, specialist subject. Avoiding OP's picks (the Python stuff would be on my list too), and in no particular order:
Bladerunner (Directors cut)
The Blues Brothers
This is Spinal Tap
Alien
Aliens
Terminator
Terminator 2
Seven Samurai
Yojimbo (+ A Fistful of Dollars)
Crouching Tiger, Hidden Dragon
Schindler's List
12 Angry Men
Rear Window
The Good, the Bad and the Ugly
Memento
Dune (the Lynch 1980's one)
The Princess Bride
The Cornetto Trilogy (Sean of the Dead, Hot Fuzz, The World's End + Baby Driver)
Die Hard
Pulp Fiction
Fight Club
The Silence of the Lambs
Se7en
The Usual Suspects
2001 A Space Odyssey
Platoon
Lock, Stock and Two Smoking Barrels
Trainspotting
My Neighbour Totoro
Do The Right Thing
The Thing (John Carpenter version)
Some they've seen, most they haven't yet.
Did @chunes@lemmy.world stutter? They never made any sequals.