Supergirl blew 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 major spoiler for the episode titled Human for a Day. In it, we learn Hank Henshaw's true identity. And it brought an iconic DC Comics character to the screen that no one was expecting. Turn back know if you don't want to know!

Yes, on last night's episode of Supergirl Season 1 titled Human for a Day, the show dropped possibly the biggest bombshell of the fall TV season, if you don't count the unexpected visitors who showed up on Fargo Season 2 last night. For months, fans have assumed that David Harewood was playing Hank Henshaw and would eventually turned into Cyborg Superman. 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 Harewood is actually playing J'onn J'onzz. Yup. He is the Martian Manhunter! Executive producer Andrew Kreisberg had 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 how Supergirl has 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 of Supergirl 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 Harewood promises 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."

KSiteTV has an interview with David Harewood on 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.

Related: Supergirl Season 2 Flies to The CW

Titled Hostile 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!