What about Total Recall…I remember mutant humans. Any aliens?
Project: MoonBase (yes, I know it was three failed TV episodes spliced together, but it was (God knows why!) released theatrically (and made three bucks, iirc, two of which were RAH and Ginny sneaking in with their faces covered, I believe :D).
Sir Rhosis
Well, we don’t see the aliens, but they built the device that Arnie finds at the end of the movie. Does it count if the aliens are apparently extinct?
Yup. Dead aliens still count. In fact, everyone knows that the only good alien is a dead alien. 
I was thinking of movies where aliens do not, as far as anyone knows, exist.
So I was thinking about this while I was doing dishes, and I could hardly come up with anything. I guess Armageddon loosely fits the criteria, although there’s not a whole ton of space travel in it.
And Contact? It’s been a while since I’d seen it, but are there aliens implied, or were those future humans? And there wasn’t much space travel anyway.
No, that wouldn’t count. Oh well, definitely not my favorite movie anyway (I pretty much thought it sucked) and I only saw it once.
FWIW Cowgirl my interpretation of the beings in Contact was that they were supposed to be aliens but I could be wrong.
Small Clanger already said Space Cowboys. 
(I guess there’s no aliens…I didn’t see it.)
In Pitch Black there are aliens, but I could argue they’re nonsentient.
In Forbidden Planet there are alien artifacts and although we’re led to think that the big beastie is an alien, we find out it’s really the id of Dr. Morbius run amok
Lots of others:
Conquest of Sace (George Pal’s follow-up to Destination: Monn)
**When Worlds Collide
Ikarie XB-1** (AKA Voyage to the End of the Universe. European space flick circa 1960.
**Things to Come
Die Frau im Mond** (Fritz Lang’s Woman in the Moon)
From the Earth to the Moon (Not the Tom Hanks-produced HBO series, but the awful adaptation of a good Jules Verne novel)
Riders to the Stars (awful film based on a ludicrous Curt Siodmak concept, but I think it qualifies)
World Without End (The spacemen end up on Earth t the end, so they don’t really encounter aliens)
The Lost Missile – forgotten SF film with script my Jerome Bixby (Fantastic Voyage, It! The Terror Beyond Space) made on shoestring budget. I aven’t seen it in eons, but I recall it as pretty interesting.
Hey, no fair. You got my heart all beating and everything, thinking there were movies made about these.
Now I’m all depressed.
Way, Way Out!
Now I’m really depressed.
Our Man Flint
All better now.
Thunderball, with Sean Connery.
So, no microbes on up, eh? Then this would include plant life, so no distant planets with plants.
This would rule out When Worlds Collide as well as Forbidden Planet.
as well as the upcoming Firefly movie, unless every other planet has only earthlife.
They are aliens. The main alien disguises itself to look like Ellie’s father to make the meeting easier on her.
Ooohh, I remember seeing this when I was about 9 or so. Forgetten since then until now. Now I have to watch it again to see if the story was as great as I remember it.
Thanks for reminding me!
Moonraker.
Cowboy Bebop. There are no intelligent aliens, anyway.
Road to Hong Kong.
What I was goin’ for was a strict no aliens rule.
No alien trees.
No alien algae.
No alien fungus.
No alien furry critters.
No alien reptiles.
No smart aliens.
No dumb aliens.
No sex-crazed aliens.
No single-celled aliens.
No alien diseases.
No alien artificats of lost alien civilizations.
No mysterious alien technology.
No obvious alien technology.
No aliens.
And anyone who suggests the movie Aliens is going to be escorted briskly to the nearest airlock.
So, I guess Santa Claus Conquers the Martians would be right out, then?
Thunderbirds.
The Right Stuff.
Laputa. I think…
Sphere