"Unfortunately Laura, who Greg [Berlanti] and I have worked with for years going back to Eli Stone, was unable to continue in the role due to work commitments in New York," executive producer Andrew Kreisberg said in a statement. "But we are so blessed that Erica has come aboard to offer her own interpretation of Kara's mother. We had tremendous success with a former Lois Lane last season with Teri Hatcher. We know Erica will continue the proud tradition of legacy actors joining our shows and creating new and exciting takes on classic DC characters."
Durance is no stranger to the Super family, having played Lois Lane on Smallville for seven seasons. And, as the statement mentions, she's not the first former Lois Lane to join the series. Lois & Clark alum Teri Hatcher played last season's big bad, Queen Rhea of Daxam.
Season three already has a new villain, Odette Annable, who will be playing a character called Reign, a super-powerful Worldkiller from Krypton, Supergirl's home planet.