Galactus was originally a mortal humanoid named Galan from the planet Taa, who became a cosmic being after undergoing events tied to a universe existing before the current one. His origin has been expanded and refined across Marvel comics, involving a cosmic cycle in which his universe ended and a new one began, with him awakening as Galactus to sustain himself by consuming planets. He is often associated with the Witnesses of the universe and is frequently accompanied by heralds, such as the Silver Surfer, who scout and prepare worlds for his consumption. The most established version places Galactus as the sole survivor of a pre-Big Bang cosmos, who merged with the sentient energy of that universe and transformed into the planet-eating entity known in the modern Marvel continuity. This origin has been elaborated by various writers over the years, including initial framing by Stan Lee and Jack Kirby and later clarifications by Mark Gruenwald, John Byrne, Jim Starlin, and Louise Simonson, among others.