Supergirlblew peoples minds last night in a big way. And if you missed it, or are saving the reveal for a later date, you better turn around now. This story has a majorspoilerfor the episode titledHuman for a Day. In it, we learn Hank Henshaw’s true identity. And it brought an iconicDC Comics characterto the screen that no one was expecting. Turn back know if you don’t want to know!

Yes, on last night’s episode ofSupergirl Season 1titledHuman for a Day, the show dropped possibly the biggest bombshell of thefall TV season, if you don’t count the unexpected visitors who showed up onFargo Season 2last night. For months, fans have assumed thatDavid Harewoodwas playing Hank Henshaw and would eventually turned into CyborgSuperman. Nope. That’s not what happened at all! And we have two clips that reveal who he really is.

Human for a Day’s big surprise was the polar opposite of all that fan speculation. As it turns out,David Harewoodis actually playing J’onn J’onzz. Yup. He is the Martian Manhunter! Executive producerAndrew Kreisberghad this to say about introducing the Justice League character on the series, which was not a decision they came to lightly.

“Within the body of the Supergirl series, there is a Martian Manhunter series rolling throughout, it fit in with howSupergirlhas been evolving. She’s embraced her powers and stepped out into the light, and in a way, J’onn is closeted and afraid. He’s one of the most frightening-looking Justice Leaguers, but he has the purest heart.”

In episode 11 ofSupergirl Season 1, we’ll get to learn more about J’onn J’onzz’s past. That won’t happen until the show returns from it’s winter hiatus.David Harewoodpromises it will be one of the most powerful episodes to date. Here’s what he had to say about this upcoming adventure for Martian Manhunter.

“It was a very emotional episode, just thinking about the whole idea of genocide and people being burned alive. It’s going to be a very emotional and powerful episode, and fans will be really delighted to see it. Having lost his own children, [Jonn’s] got a lot of pain and melancholy, which is fantastic to play. These two girls represent something that’s very close to him.”

KSiteTVhas an interview withDavid Harewoodon the big Martian Manhunter reveal. They also sit down with Chyler Leigh, who talks about Alex Danvers' reaction to the news, and Executive producer Andrew Kreisberg. You can check those out, along with two clips from the show. Last night’s episode was the penultimate chapter in his saga, before the big Midseason finale next Monday night.

TitledHostile Takeover, Kara goes toe-to-toe with Astra when her aunt challenges Kara’s beliefs about her mother. Also, Cat is threatened with being removed as the CEO of CatCo after a hacker exposes her private and damaging emails. The episode airs Monday, Dec. 14 (8:00-9:00 PM, ET/PT) on the CBS Television Network. Take a look at all this exciting video, and let us know what you think!