Firebird is a floorless roller coaster located at Six Flags America in Prince George's County, Maryland. The roller coaster had originally debuted in 1990 as a stand-up roller coaster named Iron Wolf at Six Flags Great America. It was later relocated to Six Flags America in 2012 and renamed Apocalypse, under which it operated until 2018.

A Floorless Coaster, commonly known as a Floorless Roller Coaster, is a type of steel roller coaster manufactured by Bolliger & Mabillard where riders sit with no floor underneath them, allowing their feet to swing freely just above the track. Development of the Floorless Coaster model began between 1995 and 1996 with Medusa at Six Flags Great Adventure opening on April 2, 1999, making it the world's first Floorless Roller Coaster. Floorless Roller Coasters also tend to have 3 to 7 inversions incorporated in the layout of the coaster.