Ego the Living Planet is a villainous space-dwelling entity from Marvel Comics. Literally a sentient planetary body, he originated from a distant corner of the universe called the Black Galaxy. Since gaining sentience, Ego has traversed the stars seeking out other planets that he believes could be living worlds like himself.
Over the course of eons, in the Black Galaxy, one celestial mass developed in a radically different manner than the other planets around it. It grew to the size of a planet and developed intelligence and consciousness along with the ability to move its planet-sized mass by its own will. This planet became known as "Ego, the Living Planet". In its evolution, Ego developed organ-like masses under its surface, one of which is similar to a brain. As all sentient beings, Ego began to plan what its role in the universe would be.
Since his "awakening", Ego has wandered the universe and threatened many civilizations. He has even come to blows with various cosmic beings such as the Celestials and Galactus, threatened the Earth more than once, and destroyed whole planets in a vain attempt to "awaken" them as beings like himself. His endeavours have continuously proven to be fruitless and it seems, at present, that Ego will never encounter another living planet like himself.
Ego is a planet sized entity that has immeasurable intelligence, and incalculable strength. Its stamina and durability are god-like, and it can fly through space at warp speed. Since Ego is essentially a "living planet", it has total control over its total mass down to the molecular level. It can shift its surface to appear as if it had a giant face, or grow enormous tentacles. It can make itself look like either a paradise, to lure unsuspecting travelers to their doom, or a barren world and can use its mass to create plant-like growths or humanoid bodies to carry it consciousness. Ego has an internal organ system that has giant tunnels, or arteries, a brain-like organ that is buried deep within its surface, and digestive organs to digest the living beings it absorbs into its body. Ego also has an immune system that will attack an entity that resists being absorbed. Ego has vast mental powers that allow it to tap into energy sources such as the stars or absorbing other living entities and use that power for itself. It also has extreme telepathic abilities that are effective over interstellar distances.