One might think that someone as absurdly powerful as Superman would have no issue protecting his secret identity, but this isn’t actually the case. Very few superheroes operate without a secret identity, a secret identity is integral to making sure that a hero’s loved ones aren’t attacked in retaliation for what a hero does. With a wife, son and many close friends, Superman has a strong incentive to make sure that nobody finds out who he is.
While fans have often poked fun at how obvious Superman’s Clark Kent disguise is, his secret identity is actually something he highly values. Over the years dozens of villains have figured out the Man of Steel’s secret identity and these are the top ten most dangerous villains to ever do it.
Bizarro is one of Superman’s strangest enemies, one who actually has a number of different backstories. Sometimes Bizarro is a clone created by Lex Luthor, sometimes he’s from the Bizarro universe, and sometimes he’s something else entirely. But the first time Bizarro ever appeared was way back in Superboy #68 by Otto Binder and George Papp. This story sees Bizarro being created after Superboy is hit with a faulty laser gun that creates an imperfect copy of him. Since most versions of Bizarro are just alternate twisted versions of Superman, they’d all know Superman is Clark Kent, since after all, they are too.
One of the largest groups to know of Superman’s identity is the Bat-Family, which is a problem if one of them ever turns evil. This is best seen when a future version of Tim Drake becomes Savior, a villain hellbent on killing Superman’s son in the hopes of saving the future. This evil version of Tim Drake first appeared in Teen Titans/The Legion Special #1 by Geoff Johns, Ivan Reis, Joe Prado, Marc Campos, Sno-Cone Studios, and Rob Leigh. He becomes a significantly more dangerous threat during the storyline A Lonely Place of Living by James Tynion IV. As Savior is a future version of Tim Drake, he knows Superman’s identity just like the regular Tim Drake does.
Superman is a hero who people often define by his power, and Parasite is a villain that is all about taking those powers away. Parasite has the ability to drain energy out of people or objects, and since Superman’s power is due to the solar energy his body stores, Parasite can drain those powers. This is why it would be such an enormous threat if Parasite ever finds out that Clark Kent is Superman, which was exactly what happens in the Pre-Crisis DC continuity, when he learns Superman’s secret identity after absorbing his memories along with his powers.
One of the most dangerous things in the universe is an evil Kryptonian. The entire reason Superman is the hero he isn’t simply because of the power he has, but how he chooses to use that power. Superman uses his strength to help others, but General Zod is a villain who only cares about restoring Krypton, so he can rule over it. Because of Zod’s history with Krypton and the El family specifically, Zod has more or less always known that Clark Kent is Superman, and he’s never really cared either.
Brainiac is one of the many alien villains that Superman consistently fights, and he is one of the smartest beings in the DC Universe. This is partly due to the fact that Brainiac’s entire reason for being a villain is his quest for knowledge. Because of this, it’s extremely likely that Brainiac is aware that Clark Kent is Superman, but considering Brainiac is a universe-traveling alien, this knowledge isn’t very useful or relevant to him. Much like Zod, who Superman really is doesn’t have any bearing on what Brainiac wants to accomplish.
5 Manchester Black
Manchester Black was someone who truly thought he was making the world a better place in his own way. Manchester grew up loving heroes, but he eventually grew disillusioned with them and came to believe that the only way to deal with villains was to kill them. This has led him into conflict with Superman several times, where Manchester simply can’t believe that a hero like Superman could exist. This hatred of Superman’s pure ways eventually leads Manchester to use his psychic powers to expose Superman’s identity to a host of villains in Superman: Ending Battle by Geoff Johns, Joe Casey, Joe Kelly, and Mark Schultz. Eventually, after Manchester sees that he has become a villain himself, he uses his psychic powers to remove the knowledge of Superman’s secret identity from all the villains he’s told.
There aren’t many villains who can actually scare Superman, but Doomsday is Superman’s biggest fear. Doomsday is a monster created on a prehistoric Krypton by a scientist who tortured Doomsday for hundreds of years. Because of this, Doomsday has a hatred for all living things, but he specifically hates anything from Krypton, including Kryptonians. While Doomsday doesn’t have the intelligence to understand what a secret identity is, he can still figure out who Superman is, no matter the disguise. When Doomsday first lands on Earth he creates a path of destruction as he travels towards Metropolis, purely because Doomsday senses that Superman is there.
While Zod is certainly a dangerous villain, he’s not the first evil Kryptonian that Superman has run into. One of the very first was Jax-Ur, as seen in Adventure Comics #289 by Robert Bernstein and George Papp. At this point in comics, Superman was still often shown as Superboy and living with the Kents. This story sees Jax-Ur pulling Jonathan Kent into the Phantom Zone and taking his place. Therefore Jax-Ur would of course know that Superman is Clark Kent. After all, Jax-Ur literally pretends to be Superman’s father for a few days.
2 Lex Luthor
Lex Luthor is without a doubt one of the biggest Superman villains, if not the biggest. With the knowledge of Superman’s identity, Lex could cause untold havoc on Clark’s life, and over his time in comics, he’s found out Clark’s secret several times. Initially, Lex builds a computer to tell him who Superman is, but completely dismisses the result, refusing to believe someone like Superman would pretend to be a regular weak human. The biggest moment where Lex Luthor realizes Superman’s identity is in Action Comics #900 by Paul Cornell and Pete Woods, at the end of the Black Ring arc where Lex gains the power of God. He once again refuses to believe Clark Kent and Superman are the same person, but in current continuity, he’s come to accept it and regularly knows who Superman is.
1 The Entire World
Superman has always maintained that he stands for truth, and in 2019’s Superman #18 by Brian Michael Bendis and Ivan Reis, he decides to prove that by revealing his secret identity to the world. Superman reasons that he can’t say he stands for the truth while lying to almost everyone in his life. Because of this, every single villain on Earth knows who Superman is. Superman revealing his identity puts a lot of his friends and family in danger, and the choice is eventually reversed with Lex Luthor removing the memory from everyone except a select few. So while Superman’s identity is a secret once again, for a time, every single villain on Earth knew exactly who Superman really is.