The Flash is getting a chilly character addition this fall. The CW’s Arrow spin-off has just cast Prison Break actor Wentworth Miller as Leonard Snart, a.k.a. Captain Cold.

The freeze-gun-touting villain is one of Barry Allen/The Flash’s biggest adversaries in the DC Comics, and is the leader of the Rogues—a group of his enemies. Miller will guest star as the character in the fourth episode of the show’s debut season this fall. “We’ll be seeing his origin and the origin of the Rogues,” said executive producer Greg Berlanti.

The news was announced at the show’s Television Critics Association’s semi-annual press tour session in Beverly Hills on Friday. DC Comics chief creative officer Geoff Johns called The Flash “the most faithful DC adaptation ever.”

The panel also hinted at the addition of telepathic supervillian Gorilla Grodd, whose presence in the show’s world is teased in the pilot (there’s an empty cage shown). “Obviously that Easter egg means the world to us,” said The Flash executive producer Andrew Kreisberg. “Dawn of the Planet of the Apes is out and hopefully they’re doing the R&D for us so that one day we can see exactly what jumped out of that cage.”

And as previously announced, Robbie Amell (The Tomorrow People) will show up as one-half of Firestorm in episode three, and that the other half of Firestorm—Dr. Martin Stein—will come along as well. “I think as we evolve Firestorm, you’ll definitely meet Stein,” Berlanti said. “We actually had him in a version of the pilot at one point on the train with Barry when he was coming back from Starling.”

Another thing that will evolve: The Flash‘s red leather suit. Producers noted the suit will change over time thanks to innovations by Allen’s support team at Star Labs.