LV-426 is the name of the planet first seen in the 1977 film "Alien", starring Sigourney Weaver. On this planet, there was a derelict alien craft containing eggs of a very violent xenomorph species that had one reaction to human beings. KILL.

Ellen Ripley was the only survivor of a landing crew that stopped there in response to an S.O.S. call that was really a warning to stay the fuck away.

Stupid humans from earth colonized this planet, and upon finding Ripley in space, cryogenically frozen for the previous 50 years, send out a search party to investigate the derelict ship.

You can guess what happens next... And there are still two badass movies after it in the series...