The Acheron Queen was a Xenomorph Queen born on LV-426. She was the original leader of the Hive at the colony of Hadley's Hope, and was later encountered there by Ellen Ripley. She was ultimately killed when she was flushed into space by Ripley.
Hadley's Hope colony surveyers Russ and Anne Jorden go to the area beyond the colony to search the area on Company Orders from Carter Burke on Earth. Russ and Anne eventually discover the derelict ship and go inside to investigate, only to discover the ancient Alien egg nest. Here Russ is implanted by a Facehugger. All the eggs soon begin to hatch and start impregnating the colonists with Xenomorph embryos, which soon reach maturity and nearly wipe out the colonists. An immature female Xenomorph eventually emerges and develops into a Queen taking residence in the lower levels of Hadley's Hope Atmosphere Processor, here the warm environment is perfect for egg incubation. Once fully mature, she begins to lay her eggs.
When a squad of Colonial Marines arrives at the Hadley's Hope settlement to ascertain why there has been no contact with the settlers for some months, they track the missing humans to the Atmosphere Processor and there they discover a number of the settlers cocooned to the walls, some still alive. At the request of one of the suffering hosts, the marines began to kill the unfortunate settlers. The Colonial Marines are ambushed by waiting Xenomorph Warriors and are forced to retreat. Ellen Ripley, who supervised the Colonial Marines' mission, later came face-to-face with the Queen during her attempt to rescue Newt, a survivor who had been taken by a warrior. Ripley threatened to destroy all of the eggs in the Royal Chamber if she and Newt were attacked, and the Queen signaled her circling warriors to let them leave. But, when one of the eggs hatched, Ripley incinerated the eggs with her flamethrower and shot the Queen's Eggsack with her grenade launcher. Enraged, the Queen detached herself from her eggsack and pursued the fleeing humans through the increasingly unstable structure.
The Queen follows Ripley and Newt in an elevator to the landing pad where she cornered them at the ledge. Ripley and Newt escaped in the dropship, rescued just seconds before the Atmosphere Processor exploded. However, the Queen clambered up inside the dropship's landing gear compartment at the last minute, and so escaped the nuclear meltdown that atomized her Hive. A short while later, in the main hangar of the Sulaco in orbit, the Queen emerged from her hiding place, ripping the android Bishop apart and setting upon Newt (possibly to secure her as a host for the beginnings of a new Hive or perhaps simply to kill her for revenge). She was foiled by Ripley, who fought her off with a power loader. The Queen was then thrown into and then expelled out of an airlock and was pulled by LV-426's gravity, where either re-entry or the fall killed her. But even then she was not entirely defeated, as before her final battle she had laid the egg that would hatch a Super Facehugger that would eventually cause Hick's and Newt's death and infect Ripley with another Queen embryo.