So, I was ready to fall asleep but figured 'I wonder if there's one last good thing to watch before I go to sleep.' and I saw Forbidden Planet was on TCM. I had always heard of it and it was good, but was never too interested in Sci-Fi beyond a 'dabbling' level, but after this movie, I'm eager to see more older 50s-60s good Sci-Fi films. Since I know I've seen a few Science Fiction fans here before, can any of you name some good 'retro' science fiction cinema classics?

I had a marathon of 50s sci-fi films on Netflix a few months ago, but can't remember the names... My favorite was something like The Man From Planet X or something like that.

The Day the Earth Stood Still
Planet of the Apes
Village of the Damned
Fiend Without a Face

The Haunting (horror, but omg it's so good)
The Creature from the Black Lagoon
Invasion of the Body Snatchers
This Island Earth (maybe not classic, but pretty fun)
The Blob
Plan 9 from Outer Space (if you want a good laugh at a classic "bad" movie)

Any episode of The Twilight Zone (1959-64) Especially the first two seasons. This show is still very engaging, even 60 years later.

Here's a famous movie to avoid, IMO....
The Fly
The original is very silly, although the 80's version is just amazing.

If you want to go back even further, start with the original Frankenstein (1931)