Your nominations here for the best science fiction (or fantasy) movie that did the best job of rising above limited sets or cheesy effects. My picks:
Five Million Years to Earth (that’s Quatermass and the Pit to you Brits
The original Land of the Lost on Saturday morning t.v., not the horrible remake.
Since Roger Vadim just died, I shall honour him by putting in my plug for Barbarella.
Sexy future heroine Barbarella (played by Jane Fonda) even makes robots malfunction with her irresistible sex appeal.
Crossworlds - 1997
Josh Charles, Rutger Hauer
Interdimensional Action flick with fun one-liners and the cast looks like they’re having fun
Stupid people surround themselves with smart people. Smart people surround themselves with smart people who disagree with them. - Isaac Jaffee
Dark Star by John Carpenter. This was his first movie release. IIRC, it was an expansion of a film school project. Very funny at times; obviously cheap and cheesy, but not in a bad way.
Check it out! You’ll be glad you did.
Does SILENT RUNNING count as a “cheap” movie? I could stand to see that baby again. And I just found out that the musical score was composed by Peter Schickele.
Uke
Okay, I purely love “bad” old science fiction flicks, so it’s really hard to narrow this down. Really hard, because there are so many great (no sarcasm) old circa 50’s and 60’s offerings that rose above the genre stereotypes through real ideas.
So I’m taking all the classics as givens, but my nomination for most underrated: Buckaroo Banzai. Though it was thoroughly tongue-in-cheek, it still paid excellent homange through sly writing, acting and allusions to SF films past.
No taste at all,
Veb
Plan 9 From Outer Space. It was pure genius.
Ed Wood, you are sorely missed.
Anything with Tor Johnson.
Gypsy: Tom, I don’t get you.
Tom Servo: Nobody does. I’m the wind, baby.
Dark Star
THX1138
It Came From Outer Space (or anything else by Jack Arnold)
“What we have here is failure to communicate.” – Strother Martin, anticipating the Internet.
Since Lumpy mentioned a TV series in the OP, I think I can get away with this:
I nominate the late, great Dr. Who.
“Them” – James Whitmore, James Arness, Fess Parker, giant (tee hee) ants – couldn’t have cost more than fifty bucks for the special (tee hee) effects – and this movie still holds up!
Another vote forDark Star. My favorite scene is the one at the end where the commander (from Malibu) surfs a piece of wreckage into the planet’s atmosphere. What a way to go!
Also:
*Them!
The Blob
Missle to the Moon
The Crawling Eye
Earth vs the Flying Saucers
Planet of Blood
Psychomania
The Abominal Dr. Phibes
Night of the Living Dead (1968)
Omega Man[i/]
And a bunch whose titles I’ll never remember.
Ah, you gave away the ending! 
Of course the kicker is the theme song. I still find myself humming it from time to time! Classic.
Arnold…
Damn. Been years and years since I saw that movie. But I remember vividly where she burned that machine up.
Great movie.
“Tell me and I’ll forget; Show me and
I may remember; Involve me and I’ll
understand.” - Old Chinese Proverb
“The Day The Earth Stood Still”.
(“Five Million Miles to Earth” totally creeped me out.)
“Tremors”.
Ya beat me to it.
Yes, not only is Dark Star a great film, but the theme song (“Benson, Arizona”, which was apparently written by some friend of Carpenter’s just for the film) is a great song. Incidentally, the best version of it is not the one sung on the soundtrack. That version is one by someone singing in an apparently deliberately bad parody of a country/western voice. There’s a version of the song by a folk group called Clam Chowder that’s really much better. (They slightly lengthened the song too.)
Them! really doesn’t qualify as low-budget. It had a full A-picture budget, and was one of the top grossing movies of its year (that’s why there were so many imitations).
Great film, though.
“What we have here is failure to communicate.” – Strother Martin, anticipating the Internet.
I can’t believe no one has yet mentioned “Queen of Outer Space” (1958), which has it ALL—
• Zsa Zsa Gabor as the most intelligent scientist on Venus
• Sex-starved earth spacemen making out with Venusian babes in cocktail-waitress uniforms
• Joi Lansing (astronaut’s girlfiend) standing DIRECTLY UNDER the rocket, waving goodbye as it takes off
• Oh, yeah, Zsa Zsa’s also the only girl on Venus with a Hungarian accent (“Ay hayd her—Ay hay dot Quvinn!”)
• Hilarious puppet-like monsters attacking everyone
• Interchangeable spaceships (the earthmen take off in one; land in another)
• “Based on a story by Ben Hecht!!!”
—Who could ask for anything more? Wonder why this was never MST3K’d . . .
Oops. Of course, Joi Lansing was a “girlfriend,” not a “girlfiend.” Though that WOULD explain why she could withstand all that fire and flame . . .