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 Cress Williams as Jefferson Pierce / Black Lightning Caity Lotz as Sara Lance / White Canary David Harewood as Hank Henshaw / J'onn J'onzz / Martian Manhunter Tyler Hoechlin as Clark Kent / Superman Katherine McNamara as Mia Smoak Elizabeth Tulloch as Lois Lane Tom Ellis as Lucifer Morningstar Brandon Routh as Clark Kent / Superman of Earth-96 Matt Ryan as John Constantine Jon Cryer as Lex Luthor Ruby Rose as Kate Kane / Batwoman Guest Stars Audrey Marie Anderson as Lyla Michaels / Harbinger John Wesley Shipp as Barry Allen / The Flash of Earth-90 Osric Chau as Ryan Choi 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
