The Rogue (sometimes referred to as the "Alien King"), was a genetically-engineered Xenomorph created by Professor Ernst Kleist through the use of genetic and chemical engineering in an attempt to create a weapon to rival the Queen caste, and thus help rid Earth of it's xenomorph infestation.
Professor Kleist was assigned by the ZCT to oversee Project Chimera being conducted on Charon Base, which intended to breed a race of domesticated Xenomorphs through the use of genetic-engineering. Though Professor Kleist was able to create several domesticated Drones, he was unable to breed any Queens as they all would automatically die upon birth. Frustrated by his failed attempts to breed a Queen, Kleist decided to breed a Xenomorph powerful enough to usurp a Queen. Having discovered that the genes of corporate spy, John Kray were by coincidence capable of hosting a new kind of Alien, Kleist used him as a breeding host and was able to breed a new Xenomorph, which he dubbed the "Alien King." Kleist deemed it a perfect evolutionary successor to the Aliens, and hoped to have his King challenge Charon's resident Alien Queen.
Professor Kleist unleashed the Rogue upon the base's captive Xenomorph hive in order to test the Rogue of its capabilities. It begins to slaughter nearly the entire Xenomorph population with little effort. After hearing the Queen's cries, the Rogue broke out of the testing area and proceed to locate the Queen. Its recklessness, however allowing the remaining Xenomorph Drones to pour into the human sector. The Rogue continues to run rampant through the entire Charon Base, killing both Xenomorphs and Humans alike before confronting the Queen. While the Rogue was believed to be more powerful than the Queen, Professor Kleist was shocked to find the Queen was in fact the superior specimen. While the Rogue was larger and stronger, the Queen's superior speed and intelligence enabled her to easily dodge the Rogue's brutish attacks while she slowly wore it down. With the Rogue weakened, the Queen finally kills it. Unable to accept defeat, Professor Kleist used a sound cannon on the Queen until it went critical, destroying the Charon Base.
Abilities & Mannerism
The Rogue was seemingly much more aggressive and mercilessly attacked the smaller castes of Aliens. This is shown when Professor Kleist discovered the crushed corpses of the Queen's Royal Guards.
Interestingly, the Rogue appeared to ignore humans - when exposed to Kray, the Rogue examined him closely at first, but did not attack and finally ignored him completely. Professor Kleist stated that the reason the Rogue spared Kray was because he was incapacitated, therefore poses no threat to it. It was later shown that the Rogue was willing to kill the armed human guards, as it perceived them as a threat.