WARNING: The following contains major spoilers for "Marathon," The Flash's midseason premiere.

In Tuesday's midseason premiere of The Flash, longtime Team Flash member Cisco Ramon left to go on a trip across the new post-"Crisis on Infinite Earths" world to classify every change and threat the new universe has to offer, with Nash Wells keeping an eye on things while he's gone.

However, this doesn't mean that Cisco's actor, Carlos Valdes, is leaving the series, as showrunner Eric Wallace has confirmed Cisco will return. But when he does, it will involve an old enemy also returning.

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While speaking to TVLine, Wallace stated that Valdes will still be a part of the series and delved into what the future has in store for Cisco, while also being careful as to not reveal the villain's identity.

“Oh, no. No. [Cisco and Carlos] are not going anywhere,” Wallace stated. “Cisco’s off on his journey to catalog the world, but he’ll be back very quickly. And the information he learns out there in the world is going to help us solve one of the biggest things Team Flash has ever dealt with, and that involves the return of an old villain, which I won’t spoil.”

Wallace previously teased that the upcoming return of Wally West/Kid Flash in a future episode of the current season would also involve a  classic villain, though he gave no clue as to who that villain might be either.

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Airing Tuesdays at 8 p.m. ET/CT on The CW, The Flash stars Grant Gustin, Candice Patton, Carlos Valdes, Danielle Panabaker, Tom Cavanagh, Jesse L. Martin, Danielle Nicolet and Hartley Sawyer.