|This article is about the steel roller coaster at Six Flags Great Adventure. For more uses of Viper, see Viper (disambiguation).|
Viper was a steel roller coaster located in Frontier Adventures at Six Flags Great Adventure. It was manufactured by TOGO, and opened in June 1995. One of the park's most infamously troublesome coasters, the ride was closed for many different technical reasons throughout it's operation, very similarly to Batman & Robin: The Chiller. Viper was even considered to some enthusiasts as one of the worst roller coasters in the world. 
It was left SBNO throughout the entire 2001 season and was planned to be removed, even going as far as being removed from the website, park map, and guides. Originally, Six Flags Great Adventure's 2002 attraction was intended to be a direct replacement of Viper, but Six Flags later decided against it, and the ride received modifications to the track and restraints and reopened on March 29, 2002. After two more seasons, it closed in September 2004 to make way for El Toro.
In 1990, Six Flags Great Adventure had five roller coasters, but due to the ride rotation program and the purchase of Batman: The Ride, the park was down to only three by the end of 1992. Batman's opening brought the park back up to four coasters in 1993. At that point a decision was made to buy a new coaster to get the park's coaster count back to five.
Ultra Twister, the ride that had previously been in the spot of where Viper eventually went, had been located to Six Flags AstroWorld in 1990, and had seen massive popularity at its new home. Because of this, the ride's manufacturer, TOGO, was chosen to manufacture a similar attraction as a sort of "spiritual successor" to Ultra Twister that would also tie in thematically to the new Frontier Adventures section of the park.
Initially the new coaster was supposed to be themed after the Oscar-winning 1992 film Unforgiven, but market research done by Six Flags had deemed that the R-rated film was too dark of a theme for a generally family-friendly theme park. So in place, they went with Viper as the main theme, a giant snake that lives in the Southwestern desert.
Construction of Viper began in September 1994, and concluded in April 1995. Prep work for the ride began at the end of the 1994 season, clearing the remnants of Ultra Twister. One small structure which had been part of the Ultra Twister’s infrastructure was left in place near the ride entrance, and the steel building was clad in rustic wood siding to fit the area's new theme. The queue was designed to follow along the sidewalks of a ghost town. The new ghost town buildings built were elaborate set pieces with no real structure behind them. The area between the queue and the sidewalk became a southwestern desert, complete with cacti (both real and faux) and aged western props of all kinds.
- "We've created a three-acre fantasy experience. Guests will be transported to an old ghost town where they'll encounter the sights and sounds of the old west, and ultimately discover the venomous VIPER. Like Batman: The Ride and the Right Stuff Mach 1 Adventure, we've created a whole story line for our Guests to follow and enjoy. Anyone can build a ride. At Six Flags, we build fantasy adventures."
- ―Then-park president Scott Bernstein in the press release for Viper; February 1, 1995