With the MCU embracing its cosmic sector more than ever, the induction of Galactus seems inevitable, yet the perfect opportunity to introduce him already happened in Phase 3. Galactus and his herald, the Silver Surfer, need an MCU do-over and the best way to do that is by deviating from the most obvious path of bringing them in with the Fantastic Four. Not only is a shake-up essentially necessary at this point, but Galactus could be used to further expand Marvel's cosmic lore.
First appearing alongside his herald in Fantastic Four #48 (1966), Galactus, The Devourer of Worlds, is a cosmic force of nature. He feeds on the energy of whatever world that the Silver Surfer leads him to. Obviously, that creates issues when Galactus comes to Earth and his presence usually requires the intervention of the Fantastic Four, the Avengers, and whoever else Earth can spare. Galactus and the Silver Surfer made their big-screen debut in 2007's Fantastic Four: Rise of the Silver Surfer, though the film received a considerable amount of criticism for its depiction of Galactus as seemingly just a giant space cloud.
Related: If The MCU Nails Celestials, Galactus Just Might Work
The nature of Galactus means that he has few actual consistent adversaries, but there is at least one foe who continually gives him trouble: Ego the Living Planet. Debuting in 1966 (the same year as Galactus) in Thor #132, the Living Planet has had a long and heated rivalry with the World Eater. A clash between the two titans of the cosmos would naturally be a perfect way to bring Galactus and his herald into the MCU. With the introduction ofEternals' Celestials, the MCU has shown Galactus is possible to pull off in a convincing way.
Ego was killed at the end
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