According to the Hollywood Reporter, The CW has cast the second half of DC Comics' Firestorm as Victor Garber joins the cast of "The Flash" as Dr. Martin Stein. The casting was foreshadowed during a recent press op with DC Entertainment CCO and "Flash" writer Geoff Johns promising viewers they would see Firestorm this season.

Garber will make his debut in the series twelfth episode. The character of Dr. Stein was originally included in the pilot, but didn't make it to the final script.

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In the source material, Stein combines with student Ronnie Raymond to form the matter-transmuting hero known as Firestorm, with Raymond in control of the hero's body while the professor guides him as a voice in his mind, offering advise and scientific help. Raymond was cast months ago, with Robbie Amell, a CW vet and cousin of "Arrow" star Stephen Amell, set to bring the character to life.

With the addition of Dr. Stein, "The Flash" bolsters its roster of Firestorm-related characters, as villains Plastique, Multiplex and Caitlin Snow -- the civilian identity of Killer Frost -- all originated in the character's comic adventures.

"The Flash" airs Mondays at 8 p.m. ET/PT on The CW.