* Superman: Superman is one of the most powerful superheroes in the DC Universe, and he has often been shown to be capable of defeating powerful cosmic beings. In one storyline, Superman even defeated the Anti-Monitor, a powerful being who was destroying all of the universes in the multiverse.
* Darkseid: Darkseid is the ruler of the planet Apokolips and one of the most powerful villains in the DC Universe. He is incredibly strong and durable, and he possesses a variety of powerful abilities, including the Omega Beams, which can destroy entire planets.
* The Spectre: The Spectre is the embodiment of God's wrath, and he is one of the most powerful beings in the DC Universe. He is virtually invulnerable, and he can use his vast powers to destroy entire universes.
* Mister Mxyzptlk: Mister Mxyzptlk is a fifth-dimensional imp who possesses reality-warping powers. He is capable of creating anything he can imagine, and he can even rewrite the laws of physics.
These are just a few of the characters in the DC Universe who could potentially defeat Galactus. It is important to note that Galactus is incredibly powerful, and it is unlikely that any single character could defeat him without a significant amount of effort.