Just got wind that Chris Vance was cast as the Kryptonian Ex-Scientist Non. The description they have of him is pretty scary and means trouble for Kara:
... a former scientist in a league with the House of El. Non is a brutal Kryptonian military officer who is sinister, powerful and angry. Non is said to represent the opposite of everything Supergirl (Melissa Benoist) stands for, and will become her greatest threat.
www.supergirl.tv/chris-vance-cast-as-non 
