Azie Tesfai has been cast as Kelly Olsen - Jimmy Olsen's sister - in Supergirl season 4, according to Deadline.
Though Jimmy Olsen has been portrayed as having various family members in comic books, Kelly Olsen appears to be a character original to CW's Supergirl. On the show, Jimmy Olsen is played by Mehcad Brooks.
Here's how Deadline describes her: "Kelly is an intelligent and insightful woman who spent time in the military in order to pay for medical school. She’s recently discharged from the military and is currently finishing her training as a psychiatrist. She’s got a large heart and cares deeply about others.
Supergirl airs Sunday nights on CW.