Victor Garber as Professor Martin Stein / Firestorm
Brandon Routh as Ray Palmer / The Atom
Caity Lotz as Sara Lance / White Canary
Arthur Darvill as Rip Hunter: A roguish time traveler who hides the strains of being responsible for history itself behind a facade of charm and wit.
Ciara Renée as Kendra Saunders / Hawkgirl: A young woman who is just beginning to learn that she has been repeatedly reincarnated over the centuries. When provoked, her ancient warrior persona manifests itself, along with wings that grow out of her back, earning her the moniker Hawkgirl.
Franz Drameh as Jay Jackson: A former high school athlete whose pro career was derailed by an injury who now works as an auto mechanic.
Dominic Purcell as Mick Rory / Heat Wave
Wentworth Miller as Leonard Snart / Captain Cold
No Supergirl, which is a little odd if that's supposed to be based in the same universe.
later - james_nicoll pointed to a trailer:
later still - explanation for no Supergirl - that show's on a different channel to the rest, so no crossovers.
Apparently there is going to be yet another show, based on Teen Titans, on yet another channel, TNT. See the Teen Titans entry in Wikipedia:
TNT has ordered a pilot for a live-action TV series based on the Teen Titans called Blackbirds, formaly titled Titans, about Dick Grayson emerging from Batman's shadow to become Nightwing, the leader of a band of heroes including Starfire, Raven, Oracle, and Hawk & Dove. The pilot was written by Akiva Goldsman and Marc Haimes with filming set in Toronto in the summer and casting announced in May. On May 13, 2015, TNT president Kevin Reilly said that they hope to have the casting locked down by the summer and that he believes the show will be "very true" to the comics and "groundbreaking."
This has the potential to get VERY confusing!