...a robot that can turn into an entire planet. Unicron, the Chaos Bringer, hungers for the destruction of anything and everything. Essentially the Transformers' version of Satan crossed with Marvel's Galactus, he trucks around the cosmos, eating everything in sight. And by everything, we mean planets. He literally munches moons and sucks down anything that tries to get away, which few things ever do, and converts them into energy. Incidentally, while one could live on or even in Unicron, it's obviously not advised. He doesn't take well to intruders at all, and has various forms of security - antibodies, in a way - designed to pretty much hunt down whatever invades his system and drag them to an acid pit for digestion. Lucky thing you don't have to live on Unicron, huh? Well, don't count your robo-chickens (yes, those are actually a thing in Transformers) yet; in at least one Transformers continuity (Transformers Prime), the fallen form of Unicron hurled through space and matter gathered around it, forming a new planet which found orbit around a distant star. And that planet's name? Earth. Sleep well tonight, kids - wait, we have one more?