system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel/DC] Who was the first super hero to come back to life?
gpt
I think it is Jean Grey, who died as Marvel Girl, saving her fellow X-men by piloting a wrecked shuttle back to Earth, exposing herself to deadly radiation along the way. She was reborn as the Phoenix, the radiation and event propelling her abilities to a much more powerful level. Her new name "Phoenix" references this rebirth.

Superman died a little more than a decade later, defending the world from Doomsday. The mantle of Superman was then fought over by several would be Men of Steel: The Last Son of Krypton, John Henry Irons, Superboy, and Cyborg-Superman. The real Man of Steel eventually came back to life, after his apparent death he had been put in a stasis chamber to power the Last Son of Krypton, who was actually an ancient Kryptonian weapon known as the Eradicator.

Not sure if these were the first but they were certainly two of the most prominent.