J.E.N.O.V.A.

Jenova is an alien life-form in Final Fantasy VII. Jenova's genetic structure is a two-way conduit. She can both take in the traits of her prey, and also insert her own genes to turn other organisms into insane monsters. Once Jenova lands upon a new planet, she will instinctively begin to destroy every form of life she finds. Jenova was able to absorb the memories and form of her prey, hiding as their loved ones to destroy them. Once Jenova has completely destroyed a planet, she uses it as a vessel for her to travel through the cosmos to the next unlucky world. This constant destruction may have been going for millions of years before the beginning of Final Fantasy VII. Her age is unknown, but since Jenova can lay dormant for thousands of years, if needed, she very well might be older than the Planet itself.