Viper is a wooden roller coaster located at Six Flags Great America in Gurnee, Illinois, which opened in 1995. Viper is a clone of the Coney Island Cyclone and is the only roller coaster ever to be built directly by Six Flags. Viper is also the only wooden roller coaster that has ever carried this name (all the other Viper roller coasters, both operating and not, have been steel roller coasters). It was built by Rygiel Construction.
Throughout the years, Viper's queue has undergone numerous modifications to accommodate additions such as the addition of Raging Bull directly south of the ride and the entrance to the adjacent Hurricane Harbor water park directly west of the ride. Unlike most Cyclone clones, Viper provides a much smoother ride than the original Cyclone.
During its first year of operation, Viper was located in Hometown Square. With the opening of Southwest Territory in 1996, Viper was officially made part of Southwest Territory, where it and Raging Bull are the anchor attractions.
On May 24, 2013, the park announced that Viper would be one of three coasters running backwards for the first time during 2013 season for a limited time along with Batman: The Ride and American Eagle (which wasn't going backwards for the first time).