Among all the questions raised by the revelation that Mr. Oz is actually Superman's Kryptonian father Jor-El, arguably the biggest is "Why why did he choose the name Oz?"
The character admitted in DC Universe: Rebirth #1 that "Mr. Oz" wasn't his real name. "Who I am does not matter," he said. "At least, not yet. For now you can call me Mr. Oz, if you like."
Why "Mr. Oz"? The name choice hasn't been explained yet, but there are a lot of theories bouncing around - some better than others.
Early in the history of Mr. Oz - yes, he's been around a couple years now, so has a history - a leading theory for his identity was that he was secretly Ozymandias from the Watchmen universe.
That theory's been disproven, of course. Oz is not Ozymandias, but is instead Superman's biological father, grabbed from his timeline just as Krypton was destroyed. Since that moment, which scarred him significantly, he has been imprisoned and forced to watch the worst moments from the history of humanity.
But the fact that Watchmen characters are involved in the manipulation of the DCU - and specifically, we think, in choosing Jor-El and his fellow prisoners - doesn't completely discount the name "Oz" having something to do with Ozymandias.
Remember that in March 2015's Superman #39, readers were shown a tattoo on one of Oz's assistants, a woman named Janet (who just showed up again in Action Comics #989). The tattoo Janet wore on her arm looked a lot like the logo on Ozymandias' Nostalgia perfume. Subsequent Oz tattoos look different - including the one recently shown on Janet - but that original clue is tough to ignore.
So there's a chance - admittedly, a long-shot - that the original hint of the Nostagia perfume tattoo logo was referring to the character's connections to Ozymandias.
Geoff Johns - the architect of "Rebirth," creator of the "Mr. Oz" character, and author of the upcoming Doomsday Clock - strongly hinted at Comic-Con International: San Diego that Ozymandias would be seen soon, interacting with Lex Luthor.
Jor-El is fully aware of the schemes that have been attributed to Dr. Manhattan - the character we think he's calling "him" in recent issues. So maybe Jor-El is privy to the presence of Ozymandias as well, and the name pays homage to that character.
Another theory for the name "Oz" is that he's the "man behind the curtain," like the Oz character in L. Frank Baum's Wizard of Oz prose novels.
And now that readers have learned that Oz is Superman's real father - as opposed to Superman's other father in Kansas - the name might be connected to the fact that the main character in Wizard of Oz was from Kansas.
Still, it's tough to believe that a Kryptonian would be so familiar with American culture that he'd adopt a film's character with a secret identity as his secret identity. But that doesn't mean Johns wasn't familiar with the concept and adopted it for that reason, explanations be damned.
There are also still mysteries surrounding the two figures in Oz's prisons - the ones in the same hallway as Tim Drake. And some readers have shared a belief that Ma and Pa Kent could be those two prisoners, giving the Kansas connection even more weight.
Last on our list is a in idea we're calling the "best" theory because it seems to fit what we know about Jor-El and the themes that John is using in Doomsday Clock.
Plus, it's a very simple theory, without a lot of assumptions surrounding it. And if we follow Occam's razor - that simpler theories are preferable to more complex ones - it's the best one on the list.
We have to credit Jim Prescott, a commenter on a recent article we shared about Oz. As Prescott pointed out, if you flip Superman's "S" symbol, it looks like a Z inside a pentagon.
At first, that just seemed too easy, but then we remembered what the S-symbol has meant in recent continuity. As established in Superman: Birthright and referenced several times in continuity since (and even in movies and TV shows), the S-shield is not just Superman's family crest. It's also a Kryptonian symbol.
The symbol means "hope."
So not only does flipping the Superman symbol change the letter into a Z, but it also flips around the word "hope."
And, perhaps, it becomes a symbol for "no hope."
After all, the key motivation for Oz/Jor-El is that he has no hope in humanity. He wants Kal-El to leave Earth with him. Humans, he says, do not deserve Superman.
Readers got an early indication of this motivation during the character's introduction. In Superman #34, Mr. Oz pointed out that even though Clark faces tragedy every day, he "never gives up hope." He wondered aloud if Superman ever can give up hope. Years later, readers now understand why Jor-El contemplated this possibility: Jor-El wants Superman to give up his hope for humanity.
So if this theory is true - that "Oz" is merely a backwards representation of the S-shield - it has a deeper meaning linked to embracing the opposite of hope and giving up on humanity.
Of course, just because this is the best and simplest answer now doesn't mean more information might not bring another theory to light, as Action Comics continues to explore the history of Mr. Oz and his schemes against Superman.