"One of the things that most excites us about Arrow is that we go where the story takes us," Arrow executive producer Marc Guggenheim said in a statement. "Last year, the story took us to the tragic death of Laurel Lance. This year, our midseason finale reintroduced us to Laurel’s doppelgänger, Black Siren."
"We were so taken by Katie’s fearless interpretation of this character that we knew her story was not yet finished," the showrunner continued. "We couldn’t be more thrilled to welcome Katie back to Arrow as Black Siren, though as her appearances on Arrow and DC’s Legends of Tomorrow this season show, she never really left the family."