Supernatural alum Osric Chau has been cast as Ryan Choi for the Arrow-verse's "Crisis on Infinite Earths" crossover on the CW, according to TVInsider.
According to a description from that news oulet, "[Ryan Choi is a] physics professor at Ivy Town University," and "a normal guy who learns that he has a pivotal role to play in the coming 'Crisis on Infinite Earths.'"
While Chau's reported role is identified only as Ryan Choi, in comic books Ryan Choi is one of the various characters who have donned the Atom moniker.
Brandon Routh currently plays another Atom, Ray Palmer, on DC's Legends of Tomorrow but - in what could be connected - Routh will also play Superman in the multiverse spanning event, ahead of segueing out of the show in 2020.
"Crisis on Infinite Earths” will crossover Arrow, The Flash, Supergirl, DC’s Legends of Tomorrow and Batwoman in a five-episode event, with three episodes airing in December and the remaining two airing in January.