Supergirl Casts the Legion's Brainiac 5 With Defiance Alum Jesse Rath 

alum Jesse Rath in the recurring role of Brainiac 5, TVLine has learned exclusively.

Half computer, half organic life and boasting a 12-level intellect, Brainiac 5 is a member of the Legion of Super-Heroes who travels to National City from the 31st Century to help Supergirl and the DEO battle Reign, the villain that L-Corp CEO Samantha Arias (played by Odette Annable) is on track to becoming.

Of course, Brainiac 5 in DC Comics lore has at times been

than a colleague of Supergirl’s. And as co-showrunner Andrew Kreisberg previously told TVLine of the character’s arrival, “Someone down the road will like Kara a

Rath will first appear in Season 3, Episode 10 — which is titled “Legion of Super-Heroes.” (In the comics, Mon-El aka Lar Gand/Valor also has an affiliation with the Legion, as does Saturn Girl — to be played by Amy Jackson.)

Update: “Episode 10 is called ‘Legion of Super-Heroes,’ and you can’t call it that without having the Legion of Super-Heroes in it,” Kreisberg tells TVLine. “We’ve hinted at the Legion going back to Season 1, when we saw the Legion ring in the Fortress of Solitude, so the Legion will have a presence.

“Supergirl is about to face her greatest nemesis in the three years that we’ve been doing the show — we feel that Reign is the best villain we’ve ever had — so it’s going to take all the allies that she can muster to take Reign down,” the EP adds. “The Legion will be playing a big part in that.”

alum James Marsters in the Season 10 episode “Homecoming.”

continues its season tonight at 8/7c with Episode 5, “Damage.”

, where he played Castithan crime family member Alak Tarr, Rath’s previous TV credits include

, a prequel to the bestselling videogame Assassin’s Creed II. A diehard comic book fan, Rath is also one of the creators and stars of the popular web series

, or for any other show? Email InsideLine@tvline.com and your question may be answered via Matt’s Inside Line.

If you like TVLine, you\'ll LOVE our weekly newsletter. Click here to subscribe.

Grey\'s Anatomy EPs on Sudden Death of Meredith/Nathan Love Story: \'So Many Things Go Into These…

Roseanne Revival: Go Behind the Scenes With 25+ Set Photos

Supergirl Casts the Legion\'s Brainiac 5 With Defiance Alum Jesse Rath

2Lord of the Rings TV Series Adaptation Eyed, With Amazon a Potential…46

3Grey\'s Anatomy EPs on Sudden Death of Meredith/Nathan Love Story: \'So…41

4Fall TV Premiere Awards: Worst Death, Most Skin, the Biggest WTF? and…36