Clark Kent is Superman. With a heart of gold and a veritable laundry list of superpowers, Kent patrols Metropolis while fighting for "truth, justice, and the American way." Superman is the original superhero, as Kent first donned the red and blue tights in the pages of Action Comics #1 way back in April 1938. For nearly an entire century, Superman has been an international icon: There have been radio serials, movies, television shows, and so much merchandise you can't even keep track of it. Clark Kent's Superman is a bona fide legend... but Superman hasn't always been Clark Kent.
Sometimes, Kent gets pulled off-planet and needs a replacement Superman to take charge in his stead. Sometimes, Kent switches costumes with another hero for pure comedic effect. On more than one occasion, Kent gets body-swapped against his will. There was also the time DC Comics offed Clark Kent, garnering widespread mainstream media attention, and used a whopping four Supermen to replace him. Taking other members of the Clark Kent/Kal-El family out of the equation - apologies to Supergirl, Krypto the Superdog, and Jon Kent - here are the characters who have taken up the mantle of Superman for a day (or longer).
Grant Morrison and Frank Quitely's All-Star Superman is one of the most celebrated Man of Steel comic books ever created. The series won numerous awards at the time of its release and has gone on to become one of the most well-regarded Superman stories of all time, with IGN even calling it the best Superman story of all time on its list of the "25 Best Superman Comics and Graphic Novels."
In All-Star Superman #3, Lois Lane drinks a potion that Clark Kent gives her as a birthday present, granting her all of the powers of Superman. "You're serious," she asks. "I get to be like you? For a whole day? Bring it on." What follows is an utterly delightful tale of Lois and Clark being superpowered together, even getting to lock lips on the moon.
While DC's 2011 reboot, The New 52, has come and gone with the advent of 2016's re-reboot, DC Rebirth, that doesn't mean interesting things didn't happen in the pages of DC's failed relaunch. In the pages of 2014's The New 52: Futures End, a masked Superman appears while Clark Kent is off-world. While the identity of this character is a mystery for a bit, it turns out to be none other than Shazam himself, Billy Batson, acting with the consent of the Justice League.
While the character has gone on to have more widespread fame outside of the comic book fandom thanks to the 2019 film Shazam!, Batson has been well known in comics circles for years. In an interview with CBR in 2014, The New 52: Futures End writer Dan Jurgens stated, "Shazam is absolutely an A-lister."
In some classic goofy hijinks, Bruce Wayne (you might know him as Batman) has ended up wearing the actual Superman costume on a few occasions. In 1954's World's Finest Comics #71, Batman and Superman come up with a truly ingenious plot to confuse Lois Lane after she sees Clark Kent changing into his Superman outfit: switch costumes! In a mystifying plot that sees Lois unmask Kent as Batman and witness Wayne change out of the Superman costume, somehow both secret identities stay intact even though Lois is a world-class reporter.
During 2017's Batman #37, writer Tom King has Batman, Superman, Catwoman, and Lois Lane all switch costumes in order to attend their double date during "Superhero Night" at the Gotham County Fair. While it is funny to see the gruff Bruce Wayne in the real Superman outfit, nothing beats the visage of Clark Kent in Batman's costume wearing glasses.
You might remember John Henry Irons as being the titular character of 1997's Shaquille O'Neal-starring box-office bomb Steel. Fortunately for comics fans everywhere, the John Henry Irons of DC Comics fares much better than his movie counterpart.
Spinning out of the pages of 1993's massive "The Death of Superman" event, Irons seeks to take on the mantle of Superman after Kent's demise at the hands of Doomsday. Irons is an engineer and inventor with a genius-level intellect, evidenced by his striking mechanized armor suit, who has become a mainstay in the pages of DC Comics in the 25+ years since his inception. Since the return of Superman, Irons has been affiliated with iconic DC names like the Justice League, Suicide Squad, and S.T.A.R. Labs.