Garber, a Tony nominee for Damn Yankees, Lend Me a Tenor, Little Me and Deathtrap, will play one-half of the DC Comics entity Firestorm, Dr. Martin Stein.
As previously reported, Andy Mientus has also been cast in the series and is set to appear in episodes 11-12 of "The Flash."
"The Flash," which premiered Oct. 7, is developed by writer/producers Greg Berlanti, Andrew Kreisberg and Geoff Johns. It is based on the DC Comics character Flash (Barry Allen).
Visit CWTV.com/shows/the-flash.