Ego

Played by Kurt Russell

Ego is a Celestial, a living planet who can project a humanoid form and travel the galaxy, driven by a millennia-long plan to seed his own genetic material across the universe and eventually terraform all of reality into an extension of himself. He fathered Peter Quill in pursuit of a partner with matching Celestial power, only for Peter and the Guardians of the Galaxy to destroy him and his plan. Read more →

First turns up in Guardians of the Galaxy Vol. 2.