Many astute Metroid players who are also fans of sci-fi/horror films have noticed a number of similarities between the Metroid game series and the Alien movie series -- so many that it's entirely possible that the concept for Metroid was directly inspired by the Alien films. Here, then, is a breakdown of some of the more obvious similarities between the two franchises.
Metroid
* Sci-fi story featuring tough woman as a main character.
* Antagonists are gooey creatures that like to attach themselves to your head.
* Features a miniboss named Ridley.
* Ending sequence involves her escaping by the skin of her teeth from a complex that's about to self-destruct.
* Female lead ends up scantily clad near end of game (if you play your cards right).
Alien
* Sci-fi story featuring tough woman as a main character.
* Features gooey creatures that like to attach themselves to your face.
* Directed by Ridley Scott.
* Ending sequence involves her escaping by the skin of her teeth from a complex that's about to self-destruct.
* Female lead ends up scantily clad near end of film.
Metroid II
* Involves going to the source of more of the alien menace, Planet SR-388.
* Plot is a hunt for all the alien creatures you can find and kill.
* Final battle with the Queen Metroid.
* Metroids hatch out of slimy eggs fused to the floor by their own filth.
* Once again, female lead winds up scantily clad near end of game.
Aliens
* Involves going to the source of more of the alien menace, Planet LV-426.
* Plot is a hunt for all the alien creatures the Space Marines can find and kill.
* Final battle with the Queen Alien.
* Facehuggers hatch out of slimy eggs fused to the floor by their own filth.
* Once again, female lead ends up scantily clad near end of film
Super Metroid
* Displayed a bond between female lead character and alien.
* Metroid sacrifices itself at the end.
Alien 3
* Displayed a bond between female lead character and alien.
* Ripley sacrifices herself at the end.
Metroid Fusion
* Samus is fused together with a Metroid.
Alien Resurection
* Ripley's DNA was fused together with xenomorphs, resulting in Ripley clone.
The real text is available here.