Not obscure, or never seen before, as so many lists like to tell you. But, not as popular as Star Wars either.
Peter Weller, Daniel Stern, Ernie Hudson (who may have been in every movie in the 80s), and a very, very hot Amanda Pays are deep sea miners. They find something on the ocean floor, it mutates and kills them. You should check it out. As a child, I mainly remember her shower scene.
Enemy Mine (1985)
Denis Quaid, Lou Gosset Jr. Yes, that is Lou Gosset Jr on the left. Opposing space fighters crash land on a hostile alien planet. Eventually they must work together to survive. I loved this movie as a kid. Also made me appreciate turtles.
Probably no one you have heard of. I honestly don't remember. Vampire Aliens invade London. Also, boobs. I was 10 when I saw this, I remember boobs.
Jeff Bridges, Karen Allen. A woman's dead husband reappears, but is actually an alien that needs her help. Big chase from the government. Think Thelma and Loiuse meets Powder. I cried at the scene with the dead deer. (In this movie and Powder actually.)
*batteries not included (1987)
Jessica Tandy, Hume Cronyn, Elizabeth Pena. NY apartment building tenants meet small robotic aliens that are adorable. I made my mother take me to the theater to see this. She ended up loving it too.
The Last Starfighter (1984)
I have no idea who is in it. This movie was a six year old me's wet dream. Kid plays a video game at a local convenience store (#CoinOpMasterRace) until he finally beats the impossible last boss. He is then whisked away by aliens to save the Galaxy from the evil Kodan Armada. I watched this at least once a week as a child.