Last night's episode of Supergirl threw fans a major curve ball last night when the true identity of Hank Henshaw was revealed.

Please note that the following contains spoilers.

On last night's Supergirl, Hank Henshaw (David Harewood), former CIA agent and head of the Department of Extranormal Operations (DEO), revealed that he, himself, was not human. But he wasn't the non-human that DC Comics fans expected.

In the comic books, Hank Henshaw is the villainous Cyborg Superman. After exposure to radiation in space, Henshaw's human body deteriorates, so he transfers his consciousness to the LexCorp mainframe and adopts a robotic body. Eventually, he blames Superman for the radiation mishap that resulted in his wife's death, and vows to exact revenge upon the Man of Steel.

However, on Supergirl, the man posing as Henshaw is someone else entirely.

Yes, that's right: on Supergirl, Hank Henshaw is J'onn J'onzz, aka Martian Manhunter. He's the last surviving member of the Martian race and has come to Earth as a refugee, much like Supergirl (Melissa Benoist). But as head of the DEO, he also protects the Earth from other alien beings that might seek to harm it.

In the comics and animated series and movies, Martian Manhunter is an ongoing member of the Justice League, seeking to protect Earth along with fellow Justice Leaguers Superman, Batman, Wonder Woman, Flash and others.

"Within the body of the Supergirl series, there is a Martian Manhunter series rolling throughout, it fit in with how Supergirl has been evolving," said executive producer Andrew Kreisberg to "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 last night's episode, Henshaw shares this revelation with Alex (Chyler Leigh), stating that one other person knows his true identity (he doesn't say who, but it's likely Superman). He reveals that the real Hank Henshaw died the same night as the girls' father did. He took up Henshaw's identity to protect himself from being hunted by the DEO.

"It was a very emotional episode, just thinking about the whole idea of genocide and people being burned alive," said Harewood. "It's going to be a very emotional and powerful episode, and fans will be really delighted to see it."

Supergirl airs on CBS on Monday nights.

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