Supergirl Executive Producers Talk Hank Henshaw Twist

Spoilers ahead for tonight's episode of Supergirl, titled "Human For A Day."

Additional reporting by Ashley Robinson.

With Supergirl powerless and her sister trapped in the DEO offices following an earthquake, how does the team deal with the threat of a villain as powerful as Jemm?

Well, the answer is truly, truly outrageous: DEO Director Hank Henshaw revealed himself to in fact be J'Onn J'Onzz, the Martian Manhunter.

It's actually been a fairly popular theory on the Internet since the very first time Henshaw's eyes lit up. Most fans gravitated toward the more obvious answer that Henshaw would be...well, Hank Henshaw. In the comics, Henshaw was an astronaut who gained the power to control machinery after an accident that killed the rest of his crew. Ultimately, he became a deadly villain who called himself the Cyborg Superman (long story).

And, according to showrunners, that was the original plan: Henshaw would be evil.

"In the comic books, he's very revengeful and has a deep, deep loathing for Superman," actor David Harewood told me at Comic-Con International: San Diego this summer, during the same roundtable event where producers hinted there were big changes afoot now that the pilot had been ordered to series. "I'm hoping to bring elements of that in, but if I can keep it original and still bring the Hank Henshaw fans with me, I think I will have succeeded in doing my job."

It was actually Harewood whose appearance and demeanor reminded producers of Martian Manhunter -- and became a game-changer.

Here's series executive producer Andrew Kreisberg on how the big change to Henshaw's character came to pass:

"So, we were on the set of the pilot and we were talking about, as it happens when you're on the set of the pilot, you start seeing the sets, you start seeing the actors and you start thinking about, well, what we could do next and all the possibilities that there could be and we were - all of us - just so in love with David [Harewood] and, so happy to have him on the show and just loved everything that he was doing with Hank [Henshaw] and Geoff Johns and Greg Berlanti and I were standing there and we were saying collectively amongst us, 'It's so funny we cast David because he's got those weird ears, you know? He's got a little bit of alien ears and I don't remember which one of us said it, but it was like, 'Oh, if we were ever gonna make a Martian Manhunter show or something, David would have been the perfect Martian Manhunter.' and it was Geoff who said, "Well, why can't he be?" [laughs] and we looked at each other and started, like, 'Well, wait a minute!'

"And, then we started thinking about everything that was happening in the pilot and the, sort of, notion - because we already had the Hank Henshaw idea, you know, sort of, set up that we would be playing this, sort of, bad secret that he was holding and, then we started thinking about - what if it's a good secret? What if it's, like, the reverse of the Reverse-Flash? That you think he's bad, but then he turns out to, not only be good, but, literally, the most good person in the DC Universe.

"And, then we started thinking about what all of Hank's, you know, 'cause originally Hank was gonna have, obviously, a different backstory - everything they said in the pilot - and then we were like, "Oh, actually, you know, if he survived Mars and came here and his whole goal was to protect Earth and not let Earth suffer the same fate as Mars, well, then he's doing exactly what Kara says and what Astra says, which is, 'Not here. Never again.'

"And, you know, he's had to, like, sort of, lead this crazy existence being Hank Henshaw and he doesn't want Supergirl around - she could mess everything up - and we were like, "Oh, it actually all fits." and, then we started talking about what the feasibility of it was.

First we had to tell David, 'Oh, by the way …' [laughs] and, you know, he was so funny because we - Ali [Adler] and I took him out to lunch - and he was like, 'I'm not gonna be Shrek am I?' [laughs] and - that was his biggest fear - and we said, 'No, no, no, no,' and we went to Armen [V. Kevorkian]."

Kevorkian, of course, is the visual effects guru that made Gorilla Grodd and Killer Shark happen over on The Flash.

And it mostly fits: Henshaw in the comics was scarred by the loss of his wife and his two best friends. J'Onn is defined by the loss of his world -- most especially his wife and daughter -- to a psychic plague created by his demented brother. That means when Henshaw said a few episodes ago that he "used to" have a family, it could fit either character. So, too, the glowing, red eyes...although it will be interesting to see just how a Martian defused that bomb in "How Does She Do It?" That one felt more like it was in the Cyborg Superman's wheelhouse.

Regardless, the big question is how it's going to affect both Henshaw's character and the larger world of the show going forward.

"I think we've known about this great and amazing piece of Hank for a long time and it's really shaped our movements throughout, so it's been nice to have that, sort of, blueprint in play since we started this," said executive producer Ali Adler. "So what's exciting is that we finally get to share that with people and, so what's fun about that is he's got such tremendous powers, so we finally get to, you know, use to our advantage all of these things that we've had to keep a little, like, the red eyes are fun, but we want to show off what he can do and we'll definitely use that in upcoming episode."

What could that episode entail? Well, without getting too deep into details, Kreisberg had used the words "white Martians," which is something to think about. In the comics, those were the primary antagonists in the first arc of Grant Morrison's game-changing run on JLA. A race of violent and malicious Martians, they had sleeper agents all around the world and proved quite a challenge for even the "big seven" Justice Leaguers.

In the current comics, the Cyborg Superman was recently reinvented as a foe to Supergirl -- but not as Henshaw. That would be Zor-El, Supergirl's father -- or a version of him, anyway. It seems she's got some serious family drama going on...!

Where does that leave Henshaw? Well, he's been on a mission to Jupiter with the Excalibur for a decade, and has just recently returned -- finding himself face to face with the pre-Flashpoint Superman that the "other" Henshaw hated so much in the first issue of Dan Jurgens and Lee Weeks' new series Superman: Lois and Clark.

So...what's next for all these characters? We'll find out more next week when Supergirl comes back for its midseason finale on Monday at 8 p.m. ET/PT on CBS.