Wentworth Miller made his Arrowverse debut in the first season episode of The Flash called Going Rogue. As Leonard Snart aka Captain Cold, Miller would appear multiple times before becoming a regular member of DC’s Legends of Tomorrow. But his character sacrificed himself at the end of the first season. He was brought back for a few episodes in season 2, plucked from earlier in the timeline. He also made an appearance in season 3 of the Flash to help Barry steal something from ARGUS. He returned again in the Crisis on Earth-X crossover as Leo Snart aka Citizen Cold from Earth-X and he stayed with the Legends for a few episodes before returning home.
A recently released synopsis for the upcoming 19th episode of the Flash season 4 has Miller once again appearing as Citizen Cold in an episode called Fury Rogue. Here is the description:
WENTWORTH MILLER RETURNS AS CITIZEN COLD — When Barry (Grant Gustin) needs help transporting a dangerous meta, he calls on a new friend for help – Leo Snart AKA Citizen Cold (guest star Wentworth Miller). Meanwhile, Cisco (Carlos Valdes) becomes suspicious of Harry (Tom Cavanagh). Rachel Talalay directed the episode written by Jeff Hersh & Joshua V. Gilbert (#419). Original airdate 4/24/2018.
If the dangerous meta is one of the bus metas, then it has to be either Fallout (Ryan Alexander McDonald) who we’ve met before or the Folding Man who we have yet to meet. I’m curious why asking Snart for help makes more sense than Killer Frost (Danielle Panabaker) who has basically the same powers but without the need for technology. And what is with everyone getting suspicious of Harry?
The Flash returns tonight at 8 PM on the CW. Fury Rogue will air on April 24th.