The latest "Supergirl" episode "Human for a Day" provided a pretty interesting development - David Harewood's character Hank Henshaw, the former CIA agent who is now the mysterious head of the Department of Extranormal Operations (DEO) is in fact a martian himself.

And he is not just any martian. Henshaw is the comic book fan favorite Martian Manhunter, a really powerful superhero who is also a part of the Justice League.

"Supergirl" co-creator Andrew Kreisberg told Collider that they have always wanted to incorporate Martian Manhunter into the series, and because they love Harewood's performance so much, they decided to incorporate it into his storyline.

"We were just so in love with David, and so happy to have him on the show and just loved everything he was doing with Hank," said Kresiberg. "I don't remember which one of us said it, but it was like, 'Oh, if we were ever going to make a Martian Manhunter show or something, David would've been the perfect Martian Manhunter.' And it was Geoff who said, 'Well, why can't he be?'"

When Harewood learned about his character's development, he changed his approach in his role as Henshaw and finally understood why he kept giving Kara Zor-El (Melissa Benoist) such a difficult time.

"The whole idea of suppressing who you are was something I could understand, and pretending to be hiding a big secret seems much more interesting. I was also trying to wonder why he was such a (expletive) to Kara. All the way through the pilot, I was thinking: 'There's something going on here. No one can hate aliens that much. There's something that I don't know.' So, I was happy that it was Martian Manhunter because he's an alien, so it gave me a direction to take," said Henshaw.

Meanwhile, "Supergirl" costume designer Kiersten Ronning revealed the challenges in creating the outfit of J'onzz for the small screen. What was important to them, according to her, was that Martian Manhunter's costume will not clash with Supergirl's.

"(We wanted to make sure) the color palette complimented Supergirl," said Ronning. "The way it's built, it moves well. It's not heavy. Having two superheroes in capes can be difficult, so we built his more off the shoulders, where hers kind of comes over, trying to keep it masculine."

Ronning then added, "There is a red X."

Henshaw is actually a super villain in the DC Comics universe poised as the enemy of Superman, but in recent years, he has been known as one of the main enemies of the Green Lantern Corps.