Katie Cassidy is returning to “Arrow” in a big way.

The “Arrow” alum will be back as a series regular in Season 6, playing Black Siren. She will first appear in the final two episodes of the CW show in the current fifth season.

An original cast member of “Arrow,” Cassidy portrayed Laurel Lance/Black Canary for the first four seasons, before being killed off in the midst of Season 4. After she was killed, Cassidy signed a deal with the CW to appear across the DC universe portfolio of shows in a guest capacity — then she reappeared as Black Siren, the villainous Earth 2 version of Black Canary, in “Arrow’s” midseason premiere of Season 5.

“Arrow” executive producer Marc Guggenheim commented on Cassidy’s return, saying in a statement: “One of the things that most excites us about ‘Arrow’ is that we go where the story takes us. 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. 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.”

The last time we saw Cassidy as Black Siren, the character was working with Prometheus (Josh Segarra) to take down the team. She was defeated and shipped to an Argus lockup in Central City where Ollie (Stephen Amell) hoped she might be rehabilitated to become more like the Laurel he knew.

Cassidy is repped by CAA, Anonymous Content, and Jackoway Tyerman Wertheimer Austen Mandelbaum Morris & Klein.

Jacob Bryant contributed to this report.