Whizzer, originally named Willard's Whizzer, is a steel roller coaster located at Six Flags Great America in Gurnee, Illinois, United States. Designed by Werner Stengel and built by Anton Schwarzkopf, the Speedracer model was one of two identical roller coasters built for the Marriott Corporation in time for the debut of their Great America parks in 1976.
The first installation of the ride opened with California's Great America on March 20, 1976, and it operated until 1988. The second opened with Six Flags Great America on May 29, 1976, and remains in operation. Both were the last Speedracer models ever built by Schwarzkopf, and the remaining Whizzer installation is one of only two Speedracers left in existence – the other is Montaña Rusa at Parque del Café in Montenegro, Quindío, Colombia.