Brandon Routh was Superman in the 2006 Superman Returns. On the CW’s Arrowverse shows, Routh portrays Ray Palmer aka The Atom. Next season’s big crossover will have Routh return as Superman in the big Arrowverse Crisis on Infinite Earths crossover. Routh will also continue to be Ray Palmer. Tyler Hoechlin is currently Superman in the Arrowverse on Earth 38. Routh will probably be Superman from a different Earth.
This is the same Crisis that has predicted the disappearance of the Flash since the beginning on The Flash series. If the event is similar to the comics, it will lead to the merger of the multiverse into one earth. In the comics, Barry Allen died saving the Universe and was dead for decades.
In my personal opinion, Routh was a great Superman. The 2006 Superman Returns was poorly written with terrible plot points. But Routh was a fantastic Superman on screen. I am looking forward to seeing him put the cape back on.