Special Guest Stars David Ramsey as John Diggle Stephen Amell as Oliver Queen / Arrow Melissa Benoist as Supergirl / Kara Zor-El / Kara Danvers Brandon Routh as Ray Palmer / The Atom Caity Lotz as Sara Lance / White Canary Cress Williams as Jefferson Pierce / Black Lightning Katherine McNamara as Mia Smoak David Harewood as Hank Henshaw / J'onn J'onzz / Martian Manhunter Elizabeth Tulloch as Lois Lane Tyler Hoechlin as Clark Kent / Superman Matt Ryan as John Constantine Tom Ellis as Lucifer Morningstar Jon Cryer as Lex Luthor Brandon Routh as Clark Kent / Superman of Earth-96 Ruby Rose as Kate Kane / Batwoman Guest Stars Audrey Marie Anderson as Lyla Michaels / Harbinger Osric Chau as Ryan Choi John Wesley Shipp as Barry Allen / The Flash of Earth-90 Wentworth Miller voices Leonard AI Ashley Scott as Helena Kyle / Huntress Stephen Lobo as Jim Corrigan / The Spectre Uncredited Dina Meyer voices Barbara Gordon / Oracle
