'Supergirl': Who Is Brainiac 5?

In tonight's midseason premiere of Supergirl, not only will audiences get to see Mon-El and Imra Ardeen/Saturn Girl suit up as the Legion of Super-Heroes for the first time in the series, but they will be introduced to another iconic member of the heroic team: Brainiac 5

Back in November, The CW cast Defiance's Jesse Rath in the role of the half-computer, half-organic lifeform with 12th-level intellect turned superhero. It's a role that former showrunner Andrew Kreisberg hinted might have a romantic angle with Kara Danvers/Supergirl (Melissa Benoist) later on in the series. While that might not be quite what some fans want to hear, one thing that is sure to make everyone happy is that he's there to help wake Kara up from the coma she's been left in following her defeat by Reign.

But who is Brainiac 5? If you've been asking yourself that, you're in luck. We have what you need to know about the super smart hero.

In comics, Brainiac 5 is a green-skinned, blond-haired native of the planet Colu. He's descended from one of Superman's enemies, Brainiac. Well, technically, he's descended from Brainiac 2. Brainiac 5, real name Querl Dox, joined the Legion of Super-Heroes as a way to atone for his ancestor's crimes and misdeeds. As a member of the Legion, Brainiac 5 is particularly significant. He invents the Legion flight ring and the anti-lead serum that, in comics, allowed Mon-El to leave the Phantom Zone. He also has a few misses with his inventions, namely the super computer Computo which tries to take over the world.

Brainiac 5 also has a long-standing crush on Supergirl, though in comics his affections don't always inspire positive things. At one point, a somewhat unstable Brainiac 5 creates a robot duplicate of Supergirl and convinces himself that it's the real, true Kara Danvers. He also ends up joining up with the villain Stargrave briefly after Stargrave managed to convince him that he was his father. However, even with some missteps, Brainiac 5 is still a valued member of the team, and, as on Supergirl, he is among the Legionnaires who end up trapped in the 20th century following DC's Zero Hour reboot event.

As for what Brainiac 5's path on Supergirl will look like, only time will tell, but one thing is for certain: with Supergirl down and Reign (Odette Annable) able to unleash her wrath on National City unchecked, the DEO and the rest of the citizens of National City will need all the help they can get -- including Brainiac 5's 12th level intellect -- to stop the Worldkiller.

Supergirl airs Mondays at 8/7c on The CW.