Special Guest Stars Caity Lotz as Sara Lance Grant Gustin as Barry Allen Melissa Benoist as Supergirl Danielle Panabaker as Caitlin Snow Melissa Benoist as Kara Zor-El (Earth-X) / Overgirl Victor Garber as Martin Stein / Firestorm Tom Cavanagh as Harrison Wells Tom Cavanagh as Eobard Thawne / Reverse-Flash Candice Patton as Iris West Dominic Purcell as Mick Rory / Heat Wave Colin Donnell as Tommy Merlyn (Earth-X) / Prometheus Chyler Leigh as Alex Danvers Franz Drameh as Jefferson "Jax" Jackson / Firestorm Uncredited Stephen Amell as Oliver Queen (Earth-X) / Dark Arrow
