No specific details or casting has been announced but The Flash EP Andrew Kreisberg teased: "He's going to be faster than the Reverse-Flash, faster than the Flash, and it's going to be very hard to catch him. Zoom is going to be terrifying and scary and fast, and it's going to be all kinds of cool."
Zoom is originally a Wally West villain named Hunter Zolomon whose father was a serial killer. His origin story is actually pretty cool in that while attempting to understand the criminal mind, he joined the FBI and ended up as a criminal profiler in Keystone City. Eventually, Zolomon is left paralyzed in a prison breakout by Gorilla Grodd and asked Wally West to use the time travelling cosmic treadmill to undo the accident; however, when Wally refused, Hunter attempted to use the treadmill himself, which resulted in another accident giving Hunter his "Zoom" powers. Hunter takes a turn for the worse deciding that Wally needs to suffer a personal tragedy as well and becomes Zoom.
Obviously, we could see similar elements playing into The Flash series as Grodd and the treadmill were featured in Season 1, but they will just use Barry in place of Wally.
Should be good.
The Flash Season 2 premiers Tuesday, October 6th on the CW.