The CW

Season 5 of ‘Supergirl’ is introducing the League of Ancients, from the 2002 ‘JLA’ comic book storyline ‘The Obsidian Age’, created by Joe Kelly and Doug Mahnke.  ‘Stranger Things’‘ Cara Buono has been cast to play Gamemnae, while Mitch Pileggi will portray Rama Khan.  Both roles are recurring, so they may not be the Big Bads of the season, but they will appear in multiple episodes.

Via Deadline:

DC Comics
Cara Buono joins Supergirl

Gamemnae, an ancient alien, who with others of her kind, have been safeguarding the Earth from the follies of humanity throughout the ages. Gamemnae’s aim is to use technology to subjegate humans. Gamemnae is cunning, witty, ruthless, and always ten steps ahead of her adversaries. Gamemnae’s agenda puts her into conflict with her would-be allies and on a collision course with Supergirl.

Cara Buono may be best known for playing lusty housewife Karen Wheeler on ‘Stranger Things’.  She also had the recurring roles of Martine Rousseau on ‘Person of Interest’, Faye Miller on ‘Mad Men’, Sheriff Anna Turner on ‘The Dead Zone’, and Kelli Moltisanti on ‘The Sopranos’, and has also appeared on ‘ER’, ‘NCIS’, ‘Brothers & Sisters’, ‘Hawaii Five-0’, ‘The Mysteries of Laura’, ‘The Romanoffs’, and ‘God Friended Me’.

As for Pileggi’s character, he is described as:

DC Comics
Mitch Pileggi cast in Supergirl

Rama Khan, an ancient alien who is able to control the four ancient elements — fire, water, earth, and air. Arrogant and willful, Rama Khan has been entrusted to use his powers to protect the Earth from mankind for millions of years but now his agenda puts him at odds with Supergirl as well as Lena Luthor.

Pileggi is a well-known character actor that is best known for playing Walter Skinner on ‘The X-Files’.  His most recent appearance was last week in the season premiere of ‘American Horror Story: 1984’.  He may also be known for playing Harris Ryland on ‘Dallas’ (he also appeared on the original ‘Dallas’ in the ’80s), Ernest Darby on ‘Sons of Anarchy), Larry Jennings on ‘Grey’s Anatomy’, Samuel Campbell / Azazel on ‘Supernatural’, and Dan Burroughs on ‘Medium’.

Expect more castings, as the League of Ancients also includes The Anointed One, Manitou Raven, Sela, Tezumak, and Whaler.  Manitou Raven went on to join the Justice League for a while and was revealed to be a modified version of Apache Chief from the classic ‘Super Friends’ cartoon series.

Season 5 of ‘Supergirl’ arrives at 9pm EST on Sunday, October 6, right after the series premiere of ‘Batwoman’ at 8pm.