As a domain expert in comic book lore, I can tell you that the question of who killed Superman is a significant one in the DC Comics universe. The character has "died" and been resurrected multiple times, but one of the most notable instances is from the storyline "The Death of Superman," which was published in 1992.

In this storyline, Superman faces off against a new villain named Doomsday. Doomsday is a monstrous, seemingly unstoppable creature who battles his way across the United States, leaving a trail of destruction in his wake. The two engage in an epic battle that ends with both characters seemingly dying from their fight. This event was a major milestone in comic book history and was even adapted into an animated film and later into the DC Extended Universe film "Justice League" (2017), where Superman's death is a plot point.

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Doomsday is the only one in main comics continuity to ever kill Superman; and he did so simply by beating the man of steel to death. Doomsday was killed in the battle, as well, but later healed himself and returned to life, stronger than before.read more >>