Best Of

Now that I've had a night's sleep and thought about it, here's some more:

Minority Report
The Truman Show
The Abyss
Ghostbusters
Total Recall (the 1990 film, not the 2012 version)
They Live
Wall-E
Invasion of the Body Snatchers (both the 1956 original and 1978 remake are good)
The Fly
Children of Men
Brazil (1985 film)
Monty Python's Life of Brian
Big Trouble in Little China
A Streetcar Named Desire
Easy Rider

FWIW, understanding why some of what makes these movies so great is going to be lost if there isn't a wiki session / old-man Prime there to explain what was so earth shattering about farting in Blazing Saddles, for instance, one of it's more iconic scenes.

The recommendations have all been great, but it might be worth reading up on the movie, too.

Also Top Gun is missing. Watch Top Gun.

Back to the Future (whole trilogy)
Labyrinth
Glory
Alien
Aliens
2001: A Space Odyssey
The Goonies
Scarface
Citizen Kane
Escape From New York
Tombstone
The Green Mile
The Shawshank Redemption
The Matrix
Mad Max
Mad Max 2: The Road Warrior
Mad Max Beyond Thunderdome
The Silence of the Lambs
Full Metal Jacket
Good Will Hunting
Rain Man

Pans Labyrinth
Donnie Darko
Black Swan

I don't understand people's love of Mel Brooks films. He's a good example of auteur theory, but his_ jokes_ are repetitive and tired.

Classics:

Odd Man Out
I Am Cuba
The Cabinet of Dr. Caligari
Battleship Potemkin
North By Northwest
Citizen Kane
Kurosawa's 7 Samurai

Other notable works:
Jean-Pierre Jeunet's Ameile and City of Lost Children
Wes Anderson's The Royal Tennenbaums
Les Blank's The Burden of Dreams
Pulp Fiction
Lock Stock and Two Smoking Barrels
Neil Jordan's The Butcher Boy
Y Tu Mama Tambien
City of God

Ctrl+F "The African Queen" no results.

Come on guys step up your classics game.

Casablanca, as already mentioned is an amazing choice it was my grandfather's favourite movie of all time and one of mine too.
The Big Sleep is based off my favourite novel by Raymond Chandler (Probably my favourite novel period) and is an absolutely stellar performance by the whole cast.
Following the Noir kick, The Maltese Falcon
The Untouchables
Rear Window
The Harder they Fall
Dirty Harry
Bullit
Papillon

I'm just going to throw it out there because the list is extensive, any movie starring Humphrey Bogart, Jimmy Stewart or Lauren Bacall are GOAT. I don't believe Humphrey Bogart ever had a bad film.

As for more recent films that I consider essential

Hot Fuzz
Dredd 3D (Ignore the Stallone version from 95)
No Country for Old Men
Hell or High Water
Heat
The Fugitive

Also no one mentioned this and I'm sad

ROBO COP

@Sonorous said:
@AlexDeGruven Ghost in the Machine or Ghost in the Shell?

Fix'd. Braining is hard.

Older Classics

• The Fifth Element
• Twelve Monkeys (Brad Pitt's missed Oscar opportunity, incredible performance)
• Robin Hood: Men in Tights (see also: All Mel Brooks movies because yes)
• Horse Feathers (And, to a lesser extent, most of the other Marx Brothers movies. But this one is a must-see)
• Dark City
• Close Encounters of the Third Kind
• Airplane II (masterful Shatner that cannot be missed)
• A Clockwork Orange
• Titan A.E. (Pinnacle of Bluth animation, IMO)

Modern movies that are must see because they are a master class in cinematography and/or pacing

• Ex-machina (both)
• Kumiko the Treasure Hunter (both)
• Ghost in the Shell (thx @Sonorous) (2017) (all other criticisms accounted for, this movie was gorgeous)
• Avatar (cinematography)
• Prometheus (the first 5 minutes are just... I can't even)
• Mad Max: Fury Road (because WHOA)

@Kwitko said:
Eternal Sunshine of the Spotless Mind
Being John Malkovich
Adaptation

You have no idea how happy it made me to see these here.

In addition to the above, in random order:

• History of the World, Pt 1
• Spaceballs
• Innerspace
• Explorers
• Abyss
• Die Hard 1 & 2
• National Lampoon's Vacation, Christmas Vacation, & European Vacation
• Terminator 2
• V for Vendetta
• Fight Club
• Snatch
• Das Boot
• Pulp Fiction
• Demolition Man
• A Beautiful Mind
• All Miyazaki films
• Seven Samurai
• The Cowboys