Another vote for both "Them!" (and I didn't forget the exclamation point) and "The Day the Earth Stood Still." I never miss these two.
Others worth mentioning and certainly worth checking out:
- The Lathe of Heaven (IIRC, the 1st full legth film made for PBS, but I could be wrong)
- This Island Earth
- Silent Running (Huey, Dewey, & Louie rock!)
- Attack of the 50 Foot Woman (one of the best cheesy movies of all time)
- Spirits of the Dead (kind of artsy but cool 60's film. A trilogy of Edgar Allen Poe stories, and for films buffs they were directed by Fellini, Roger Vadim, and Louis Malle. Lots of international stars from the 60's)
- 2001, The Blob, Invasion of the Body Snatchers, Frankenstein, The Invisible Man, and many others.
But don't forget the lighter side:
- Abbot & Costello Meet... (Frankenstein, the Mummy, the Wolfman, etc.)
- Bambi vs. Godzilla (probably easy to find online)
- Arsenic & Old Lace -- it still counts although it's more of a murder/comedy. Reminds me of a few family members and in-laws, too!