Along with returning heroes, a promo for the second half of The Flash's second season promises villains aplenty with glimpses of the Reverse Flash and Killer Frost.

Entertainment Weekly first confirmed Matt Letscher's return as Flash's yellow-suited antithesis despite the character's apparent death last season. This led to some speculation that this Reverse Flash could be from an alternate reality.

Seen briefly when Barry traveled through the Speed Force last season, fans have long awaited Caitlin Snow's transformation into sinister ice queen Killer Frost. In an interview with IGN, executive producer Andrew Kreisberg hinted that the story line might come later rather than sooner, but that said "I’m so excited for Killer Frost! I can’t wait!"

The Flash's midseason finale, Running to Stand Still, also introduced Wally West, who DC aficionados know becomes Kid Flash and later takes up the Flash's red mantle in the comics. When Keiynan Lonsdale, who plays West, spoke with IGN he was mum on details but said "in terms of when he becomes Kid Flash, I have no idea. That's not information that I know, but I'm hoping that it comes soon. And when the day comes, I just hope that Barry and Wally are running side by side. I think it'd be really awesome to be the sidekick. I think that'd be cool."

The Flash returns on January 19th.