UPDATE 1:25 PM PT: Following today's reveal of The Atom suit, "The Flash" star Grant Gustin shared a photo via Instagram of the Flash and Atom costumes together in S.T.A.R. Labs -- presumably from Brandon Routh's upcoming guest appearance on "The Flash."
"Superman Returns" star Brandon Routh returned to DC Comics-based live-action land last fall with a recurring role on "Arrow" as Ray Palmer, best known to fans as long-running superhero The Atom. He's been seen working on a prototype dubbed A.T.O.M., but hasn't yet suited up -- though that'll change very soon, as The CW has released the first look at Routh in costume as The Atom.
Routh makes his in-costume debut as The Atom on the 15th episode of the currently ongoing third season of "Arrow," slated to air Feb. 25 on The CW.