The CW and Warner Bros. Television announced today that Katie Cassidy will return to Arrow as the Black Siren for episodes #522 and #523 this season, and then continue in the same role as a series regular for Season Six.
Black Siren is Laurel’s evil Earth-2 counterpart. Cassidy has played this far edgier doppelganger twice before — the first time on The Flash last season and…
