Mitch Pileggi (X-Files) and Cara Buono (Stranger Things) have been cast as Rama Khan and Gamemnae in the CW's Supergirl, according to Deadline.
Buono's reported character is Gamemnae, part of an alien race who "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."
Pileggi's reported character is 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."
In comic books, Rama Khan and Gamemnae are members of the League of Ancients - an extraterrestial group introduced in Joe Kelly and Doug Mahnke's JLA run. They were a a superhero team from 1004 B.C. organized to fight a threat to Atlantis - that was secretly the JLA, traveling back in time to rescue a kidnapped Aquaman.
Supergirl returns with its fifth season beginning October 6 on the CW.