Occupation: alien experiment
Feral mind (Xenomorph)
Stealth tactics (Xenomorph)
Supernatural strength, speed, and agility ( Yautja)
cyberorganic physiology (reaper technology)
Backstory: 667 is a hybrid experiment made up of different alien races:
When 667 was created. His first instinct was to its creators and slaughter a few worlds. Gaining a reputation that rivaled the feared doomsday ( https://en.wikipedia.org/wiki/Doomsday_(comics). 667 continued to destroy and slaughter entire spieces and mutating from their remains to become the perfect apex predator. There is a rumor it could have played a part in the near human genocide (http://powerlisting.wikia.com/wiki/User_blog:Cursed_warrior_343/Corvus).
667 is not a godlike being but rarely something you would want to fight. It combines the killing traits of 5 alien races and keeps evolving from new ones.