SPOILER WARNING: The following post contains spoilers for Sideways #9, by Max Raynor, Dan Didio, Daniel Brown and Travis Lantham, on sale now.
During the New 52 reboot in 2011, DC shocked the comic book world by introducing a young, brash Superman who wore a t-shirt and jeans instead of his iconic costume. Even though that Man of Steel shouldn't technically exist anymore after he died and his history was merged with his Pre-52 counterpart, the New 52's Superman just popped up on the last page of Sideways #9.
In the "New Age of Heroes" title, the young dimension-hopping hero Sideways encounters this Superman (or someone that looks like him) while traveling between the worlds of the Dark Multiverse. After being shunted into a strange realm called the Kingdom of Benevolence, Sideways meets the Unseen, several monstrous-but-friendly versions of Superman and his allies. After taking on the world's ruler, Perrus the Benevolent, the young hero finds a mysterious underground cocoon and frees Superman from it.
If this really is the New 52's Superman, this is his first appearance in a while. Initially, he was the star of Grant Morrison and Rags Morales' critically-acclaimed run on Action Comics, which took place about five years before DC's other ongoing titles. After he ditched his casual clothes for a more modern costume, this Superman had a high-profile romance with Wonder Woman and had his secret identity revealed by Lois Lane before seemingly dying in 2016.
In the lead-up to DC Rebirth, an older Superman popped up in a remnant of DC's pre-New 52 timeline. This Superman, who was married to Lois Lane and the father of Jon Kent, found his way to DC's main reality and took over as DC's main Superman. In the reality-warping 2017 storyline "Superman Reborn," the spirit of the younger Superman reappeared one more time and merged with the older Superman to form the one, true Superman. With this merger, the history of the younger New 52 Superman was basically wiped out of existence.
So, who could Sideways' New 52 Superman be?