Galactus

He is the sole survivor of a previous universe who survived the big crunch. He was transformed during the birth of the new universe into Galactus, an entity of vast cosmic power who was also necessary for the existence of the newly formed universe. Galactus is considered one of the three essential entities within the Marvel Universe alongside Eternity, the anthropomorphic personification of the universe, and Death.

Though he wields the Power Cosmic, Galactus must feed off the energy of planets, without which he cannot survive. Towards this end Galactus scours the universe seeking planets to sustain himself. He has appointed a number of entities as his heralds, imbuing them with a portion of the Power Cosmic and setting them out to find edible worlds. Unfortunately for the Eater of Planets most of his heralds have rebelled or betrayed him. Among his heralds are the Silver Surfer (formerly Norrin Radd of Zenn-La), Terrax the Tamer (formerly Tyros of Biroj), Firelord, Air-Walker, and Nova (formerly Frankie Raye of Earth).

Recently, Galactus was changed into a star by the forces of the Earth Heroes and the Xiar empire. The results of this fact were told in the X series written by Alex Ross.