Firefly made his print debut way back in 1952's Detective Comics #184. During the Silver Age, Firefly was obsessed with lighting effects though as the years passed, lighting made way for fire and firefly became a bit more of a pyromaniac.Firefly is slated to appear for the first time in live action as a former firefighter on the series Arrow.
Firefly made his onscreen debut in The New Adventures of Batman appearing in a pair of episodes including Torch Song and Legends of the Dark Knight.
In Justice League, Firefly would return, teaming up for a jailbreak with Volcana in Only a Dream.
In The Batman, Firefly made a number of appearances as an industrial saboteur before ultimately mutating into the super powered Phosphorus in White Heat.