Airplane, time bandits, adventures of Barron Münchhausen, LA Story, the jerk, army of darkness, the shining, Chinatown, a christmas story, 12 monkeys, spaceballs, back to the future 1-3, alien(s), clerks, no country for old men, zombieland, LOTR and cartoon 1978, life of brian, labrynth, to name a few random ones off the top of my head.

Some of my favorites from my collection. All are pretty much guaranteed to be a good watch.

• Psycho
• Rear Window
• Spartacus
• 2001: A Space Odyssey
• Alien
• The Shining
• Amadeus
• Beverly Hills Cop
• Ran
• Full Metal Jacket
• Matewan
• Akira
• Do the Right Thing
• Awakenings
• The Silence of the Lambs
• Hook
• Cape Fear
• The Truman Show
• Memento
• Training Day
• Gangs of New York
• The Prestige
• There Will Be Blood
• Man on Wire
• Dallas Buyers Club
• The Look of Silence
• Trumbo
• Green Room
• The Nice Guys
• Arrival
• Silence
• Parasite

12 Angry Men, Amadeus, Gladiator, Jurassic Park, The Shining, to name a few. Practical effects always hold up better especially against early CGI.

There is a wealth of good movies out there if you're willing to dig a little. Sometimes you have to get out of your comfort zone or contextualize a film as being a product of its time. But there are great films in every decade back to the late 1920s. I mean, Wings is almost 100 years old but you can still watch it and see how it influenced films that came after.

1956 - Forbidden Planet (great sci-fi concept and earliest appearance of Leslie Nielsen I'm aware of)

1979 - Alien (sci-fi-horror fusion, strong female lead)

1984 - Gremlins (timeless practical effects, poorly-aged Chinese character)

1985 - Back to the Future (does it need a blurb?)

1994 - Dumb and Dumber (classic Jim Carrey, very quotable)

2000 - O Brother Where Art Thou (Coen brothers, Americana, great soundtrack)

2006 - Idiocracy (goofy concept, now a documentary)

I really enjoyed "The Good, the Bad, and the Ugly" when I recently watched it for the first time. Beautifully shot and the soundtrack is instantly recognizable. Great Movie.

For an older movie, I think everybody should see The Breakfast Club at least once. It does rely on some 1980s tropes, like weekend detention, and people not having cell phones, but otherwise, solid timeless movie.

For a newer one, 君の名は。 (your name.) is still the best film I've seen to date, and I've seen a lot of them. It's kind of a shame it's Japanese, and animated, because that means a lot of people will give it a pass. The film could have been made in any country with practical effects (fun fact: JJ Abrams bought the rights and a script was even penned, the city was going to be Chicago and the small town was going to be in New Mexico, in the US) but so far, it hasn't been. If it ever happens, I think it will reach a wider audience, but, until then, I'm fine with just being right while also in a minority opinion.

I can't see Alien ever aging out.

https://en.wikipedia.org/wiki/The_Thin_Man_%28film_series%29

The Thin man series is a good group of old films that capture the time it was made.

And after that watch Steve Martins file Dead Men Don't Wear Plaid.

The Princess Bride, To Kill a Mockingbird, and the 1951 version of “The Day the Earth Stood Still” are the ones I’ll throw into the ring.

Tbf the robot in the latter is very slightly dated BUT it remains a cult classic for a reason and that’s the writing. One of the earliest “hard” science fiction films and well worth a watch.

I just recently rewatched 2001 - A Space Odyssey. While some special effects certainly look dated, I'm always amazed at how ahead of of its time it was. Truly a timeless classic.

• Monty Python and the Holy Grail
• Best in Show
• Home Alone 1
• The whole suite of 1st gen Pixar movies and the Disney Renaissance movies

Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb

This is one of the few movies I can watch repeatedly and it's great every time.

Groundhog Day

Raiders of the Lost Ark

Since I have (older) kids, I can add another layer to the analysis of "timeless" movies, because for me, they would be movies that would still hold the attention of my kids.

A lot of good ones have already been mentioned, but I would like to submit "Independance Day". Yes, it is cheezy at times, but not because of its age, it always was that way. It held my kids interest. They noticed that none of the people running from the alien ships had their phones out, because smart phones didn't exist yet. And I found that they already knew the most impactful points, because of all the memes.

I think Interstellar, while not very old, will probably be timeless.

For an old movie, Blues Brothers.

Cul de Sac

Touch of Evil

Freaks

Seems no one has said the Seven Samurai yet.

Went to the theater to see a Flashback Cinema presentation of Jaws. I know I've seen it before, but I didn't remember much of any details, so it was like watching it for the first time. I've gotta say, I can see now why it's the classic it is. It was still quite scary and gave me a couple of genuine jump-scares.

I recently heard a podcast about the making of The Thing, and I think the story of isolation and those special effects hold up, so I'd throw that out there too.

North by Northwest. 1959, Hitchcock, Cary Grant.

2001: A Space Odyssey. 1968, Kubrick/Clarke. The movie by itself is an experience; paired with reading the book makes it brilliant.

Came late to the party. Most I'd mention are already there in the comments. However, Citizen Kane must be in this thread, and I believe no one mentioned it yet.

Arsnic and Old Lace

Black and White version with Cary Grant.

Very funny early dark comedy. Set at Halloween.

Happiness

Not that old, but... bullet train

The Time Machine. Transcendence, i guess? World on a Wire.

Look up the films of Jane Fonda.

9 to 5

Klute

Coming Home

Barefoot In The Park.

Barbarella.

[I just saw someone in the Criterion Closet talking about Klute. Reminded me of how good it is]

Goodfellas

The Thin Man (1934)

The dynamic between Nick and Nora (husband and wife) is great.

Masters of the Universe, because it was also corny in the 80s