Xenomorphs vs. Zombies.
Disclaimer: I do not own Alien. Zombies are Public Domain.
The survivors ran as fast as they could from the swarm of zombies. They were almost out of ammunition and all hope seemed lost. As the undead were about to catch up to their prey, a spaceship crashed near the two parties. The survivors used the opportunity to escape into a abandoned building. The zombies were distracted by the spaceship and drew closer to it.
All of a sudden, Dozens of Xenomorphs jumped out of the ruined ship and attacked the zombies. The lumbering corpses were no match for the swift alien killers. One zombie manged to get a lucky bite in before being decapitated by the Xeno's tail. Once all the zombie were dead, the Xenomorphs swarmed the area in search of living humans.
A few of the Xenos found the survivors and attacked them. The survivors tried to shoot the Xenos but the acid from the alien's bullet wounds spayed on the humans, causing their skin to melt. The remaining survivors tried to retreat but were overwhelmed by the Xenos. They were cocooned and later impregnated by Facehuggers.
Meanwhile, the Xenomorph that was bitten died but reanimated after a few hours. The zombiefied Xenomorph attacked it's fellow ailens and turned them into members of the undead as well. The remaining Xenomorphs fought against their zombiefied counterparts.
Meanwhile, one of the survivors managed to break free and escape. She happened to be a hacker and snuck into the spaceship. With a chestbuster inside of her body she knew that she would not make it. She hacked into the spaceship's programming and caused it to self-destruct, destroying her and the xenomorphs as well.
The End