So, sometimes origin stories for characters have to be amended & changed a little n the movies. Well, I had a great one for a huge character.
WARNING! SPOILERS FOR ETERNALS AHEAD!
So, Celestials pretty much hatch from planet's energy right? Picture a survivor, a brilliant scientist from a destroyed world where a Celestial hatched. Partly as revenge on Celestials for their hubris and the death of his homeworld, partially to achieve god-levels of power, because you know, POWER!! who invented a device/ship construct thingy to drain the power of an unborn Celestial right from the planet eggs, taking their godlike power and draining the planet, staying immortal but preventing billions of worlds from being born? Let's see, giant world-sucking cosmic god-being what looks like a giant robot with a flair for cool headgear? Sound familliar?