Here are my favorites. Many others are listed in this thread.
Drama:
Citizen Kane
Lawrence of Arabia
Ben Hur
The Misfits
Of Human Bondage
Educating Rita
Cool Hand Luke
Easy Rider
Born Free
Casablanca
To Have and Have Not
Gone With the Wind
The Grapes of Wrath
On the Waterfront
A Hatfull of Rain
Inherit the Wind
One Flew Over the Cuckoo’s Nest
The African Queen
Marty
To Kill a Mockingbird
Cat On A Hot Tin Roof
A Streetcar Named Desire
Lolita
Comedy:
Some Like It Hot
The Road To Rio
The Road To Bali
Airplane!
Tom Jones
Monty Python and the Holy Grail
The Pink Panther
Duck Soup
Dark Star
Young Frankenstein
Blazing Saddles
Father Goose
Out West
You Can’t Cheat an Honest Man
The Bank Dick
My Little Chickadee
Adventure:
King Kong
Raiders of the Lost Ark
Dr. No
Thunderball
Diamonds Are Forever
Goldfinger
20,000 Leagues Under the Sea
Science Fiction:
2001
Alien
Aliens
Solaris
The Illustrated Man
The Fifth Element
Star Wars (IV, V & VI)
From the Earth to the Moon
The Day the Earth Stood Still
Terminator
Bladerunner
Things to Come
Metropolis
1984
Farce:
The Producers
Cat Ballou
Dr. Strangelove
Western:
Treasure of the Sierra Madre
Giant
The Magnificent Seven
Hang 'em High
Thriller / Suspense:
Psycho
Sabotuer
The 39 Steps
The Man Who Knew Too Much
North by Northwest
Rear Window
Notorious
Vertigo
Shadow of a Doubt
Dial M for Murder
Gaslight
The Nightstalker
The Manchurian Candidate
The Conversation
Mystery:
The Big Sleep
The Maltese Falcon
Fantasy:
The Wizard of Oz
Animation:
Snow White
Sleeping Beauty
Fantasia (Original)
The Last Unicorn
Yellow Submarine
The Wrong Trousers
A Close Shave
Pinocchio
What’s Opera Doc
Porky In Wackyland
War:
Apocalypse Now
The Deerhunter
The Bridge On the River Kwai
King Rat
The Great Escape
Night and Fog
From Here To Eternity
Where Eagles Dare
Crime:
The Usual Suspects
House of Games
Godfather I, II & III
Bullit
Dirty Harry
Horror / Occult:
Dracula (Bela Lugosi)
Dracula (Frank Langella)
Frankenstein
Rosemary’s Baby
The Cabinet of Dr. Caligari
Nosferatu
Silent:
The Little Tramp
City Lights
The General
Foreign:
Steppenwolf
Doctor Redbeard
Throne of Blood
Satyricon