Untold eons after his most powerful creation, Unicron, rebelled and nearly destroyed him, the immortal mad scientist, Primacron, decided to have another go at it. This time, he created a monster entirely of energy. The result was Tornedron, a being capable of taking any form it chooses and can suck all manner of energy from anything in the known galaxy.
Its first initial form it took, beyond its energy form, was that of a monstrous spidery creature. It was also capable of splitting its form into numerous pieces if forced to hunt different prey and then reforming. Tornedron is also shown to take the form of a dragon, a tiger, a three-headed serpent, an unspecifed creature, and a dinosaur that looks like a hybrid of the Dinobots' animal forms.
The Transformers cartoon
Tornedron was created by Primacron as his second means to take over the Universe. It was first created from an atom which multiplied until it grew larger until finally it was fed an Energon cube where upon it took its energy form and ascended into space where it feasted on the energy of a comet. Sensing the danger Tornedron presented, Primacron's Assistant (now a disembodied energy being, himself), telepathically summoned all the "Primitives" among the Transformers. The Primitives were charged with defeating Tornedron, who had already sucked all the energy from Cybertron and Earth. Even both Autobots and Decepticons (including their leaders Rodimus Prime and Galvatron) have fell victim to Tornedron's consuming.
The Primitives performed rather poorly, all being drained of energy save for Grimlock, who managed to elude Tornedron. As one could expect, Tornedron quickly rebelled against Primacron just as Unicron had, and threatened to "eat" his creator. Before Tornedron had the chance (well, okay, he had a lot of chance, he was just taking his dear sweet time to do so, like a big dumb doof), Grimlock came to the rescue and randomly flipped a reversal switch which caused all of Tornedron's energies to disperse. All the energy he had devoured was returned to its rightful place, and in celebration, Grimlock destroyed Primacron's laboratory.
- He is not Galactus. Really.