Brainiac 5, a key figure from DC Comics’ Legion of Super-Heroes, is officially coming to Supergirl.

The CW has cast Jesse Rath (Defiance) in the role of Brainiac 5 according to TV Line. Rath’s Brainiac will be recurring character appearing in the third season of Supergirl.

According to the report, the half-computer, half-organic lifeform that is Brainiac 5 will use his 12th-level intellect to travel back in time to present day National City to assist Supergirl in battling the villain Reign.

In the DC Comics universe, Supergirl did follow in her famous cousin's footsteps by traveling to the 31st century to fight alongside the Legion of Super-Heroes. During that time, Brainiac 5 and Supergirl grew to be more than just teammates, and co-showrunner Andrew Kreisberg hints that the romantic angle is something the will come up later on in the series.

“Someone down the road will like Kara a lot, which will be a lot of fun,” Kreisberg says.

Brainiac 5 is the second member of the Legion of Super-Heroes to be cast on Supergirl following the announcement that Bollywood star Amy Jackson will play Saturn Girl.

"Saturn Girl is the heart and soul of the Legion of Super-Heroes. When everybody's saying, 'Legion doesn't work anymore. There's too much xenophobia. You can't change people.' Saturn Girl says, 'Yes, you can,'" said DC Chief Creative Officer Geoff Johns of the character. "Then suddenly, you realize she can read people's minds. She knows everyone's deepest darkest secrets. If she has faith, then at the base level, human beings and aliens and everybody can reach that goal, can reach achievement and have that goodness inside them. I believe her. I'm with her. And that's why Saturn Girl is so important to the Legion. She's at the epicenter of truth for the entire universe for me."

Brainiac is one of the key figures in the Legion and Saturn Girl is one of the founding members. Could the other founders, Cosmic Boy and Lightning Lad, come to Supergirl as well? Fans will have to wait for more.

Brainiac 5 also has a complex history connecting him to the Superman villain known as Brainiac, the villain who was just cast on the unconnected SyFy Superman prequel series Krypton.

Supergirl airs Mondays at 9 p.m. ET on The CW.