Illustration of a demon behind bars in a brick wall with red text that is on fire; all on a black background.
In 1979, the then Marriott Great America park redesigned their "Turn of the Century" rollercoasters in both Illinois and California rebranding them as The Demon. The storyline explained in the soundtrack for the ride is that the park missed payments on the Turn of the Century and a demon repossessed the ride. The coaster was painted black and effects such as fog and red waterfalls were added. The theme has remained largely intact since 1979, with a temporary addition of the Looney Tunes Tasmanian Devil after the parks' purchase by Six Flags and some updates to the original Marriott logo.
The Demon at Six Flags Great America has been featured as a ride during Fright Fest, the annual Halloween theme event, where participants can ride wearing 3D goggles during certain hours and witness demon attacks during their rollercoaster experience.
Marden, Duane. "Demon (Six Flags Great America)". Roller Coaster DataBase. Retrieved from https://rcdb.com/3.htm.