In this case, we are Bela Lugosi.
Okay, this is the first reply that freaked me out.
I saw Whatever Happened to Baby Jane at a college film society, probably in 1979, and found it so disturbing I could never watch it again. Victor Buono gives me the creeps even when I see him as King Tut on the Batman teevee show or Reverend Jim’s dad on Taxi.
‘Rear Window’.
Dammit. I asked my gf what her favorite movie was and she has been thinking it over. When she asked me, I mentioned Pulp Fiction, but she corrected me. Apparently my favorite is actually Jackie Brown. She is correct. She knows me better than I do.
2001: A Space Odyssey, followed by Dr. Strangelove and A Clockwork Orange.
Trainspotting…never gets old. 2nd place is a tie between The Godfather and In Bruges.
There are so many already named that I love: The Castle, Rear Window, North by Northwest, The Right Stuff, A Clockwork Orange, Casablanca… I love them all.
There are two others not yet named and they are a toss-up for me. One was critically recognized, the other not: A Room With a View and Zodiac.
The latter, despite having a cast of excellent A-list actors (Jake Gyllenhaal, Robert Downey Jr., Mark Ruffalo) and wonderful performances by supporting actors (John Carroll Lynch, Anthony Edwards, Brian Cox, Chloë Sevigny and others) did not receive much in the way of recognition. Yet the producers of this film took a complex story, wove it into a tense, creepy, compelling narrative while maintaining its historical accuracy and added touches of pure comedy, horror and pathos. I never tire of watching it.
Willy Wonka and the Chocolate Factory. There are a few that come close (Jurassic Park and The Birdcage come to mind) but my heart will always belong to Wonka.
I’ve seen and loved many noirs. Sunset Boulevard is one of my favorite movies. Blade Runner with H. Ford’s uninflected narration is still shit.
The Outlaw Josey Wales
I don’t really have one, but if I turn on the TV and “Shawshank Redemption” is on, I’m watching it till it’s over.
I wouldn’t pick it as my all time favorite. But I have watched it six times since its release, which was only four years ago.
Terminator 1. It’s been my favourite movie ever since I was about 10. I have other movies that I love despite flaws but there are no serious flaws in The Terminator, taken as a solo movie without the sequels.
Ah, this is your Spartacus moment!
I’ve been through the entire list several times now, but I can’t come up with my “all time favorite” any better than the Steve McQueen thriller with this user’s name! If it’s not “Bullitt” I can’t think what else it might be! I’ve seen that movie many times and it’s always fresh, exciting and fun!
I hesitate to mention “Rebel Without A Cause” because I think I grew past that one some time in my thirties! Same with most (if not all)) of Brando’s things. 
But I’m tempted to mention (at least) Paul Newman’s “The Hustler” in passing.
Many great movies already mentioned – enough to convince me that this is a difficult task!
A year ago, I would have said The Rocketeer, or maybe Rocketship X-M, but lately I’ve been developing a jones on Godzilla (the original Japanese-language version); it’s kinda become my rainy-day, warm feeling movie. There’s just something about a guy in a rubber suit kicking over meticulous little buildings.
He likes gladiator movies. 
Badlands - Terrence Malik’s first movie with Martin Sheen and Sissy Spacek. It was the support to something else at a midnight session, and TimeOut only gave it a mediocre review. I had seen Sheen only a few days before on TV in The Execution Of Private Slovik and that was incentive enough. It is just about the least well known American masterpiece of movie making that I have introduced to people.
The other movie I considered I also initially caught as a support - at the drive-in. Cool Hand Luke was the mere support for the vastly inferior Easy Rider.
Before the advent of video and away from big cities it was hard to keep up with movies unless they appeared on TV.
Turn up your hearing aide old man…
I chuckle as i write this… 
My Fave used to be “The Jerk” , Steve Martin.
Then became “Rain Man” …
Then became “Pulp Fiction” :
My taste and memory change too.
I cannot choose an absolute favorite single movie. Thank og a number of my faves have already been listed. Allowing me to mention “the Good, the Bad, and the Ugly”