Special Guest Stars Tyler Hoechlin as Superman / Kal-El / Clark Kent Grant Gustin as Barry Allen / The Flash Stephen Amell as Oliver Queen / Green Arrow Carlos Valdés as Cisco Ramon / Vibe Danielle Panabaker as Caitlin Snow / Killer Frost David Ramsey as John Diggle Tyler Hoechlin as Dr. John Deegan / Superman (Elseworlds) Guest Stars LaMonica Garrett as Mar Novu / The Monitor Elizabeth Tulloch as Lois Lane Ruby Rose as Kate Kane / Batwoman Jeremy Davies as Dr. John Deegan Bob Frazer as Roger Hayden / Psycho Pirate Adam Tsekhman as Gary Green Cassandra Jean Amell as Nora Fries Co Starring Claudia Kai as Young Woman