Demolitions expert Joey Rigger returned to Gotham City when his entire family was killed in separate building related accidents in a three week period. His sanity severely affected by these tragedies, Rigger became determined those buildings could not be allowed to kill again.
Using skills he had learned in the army, Rigger became the Firebug, and set out to burn all three buildings to the ground. These efforts brought Firebug into conflict with the Batman, who finally confronted the Firebug atop the towering Gotham State Building. Hoping to prevent Batman from thwarting his final fire, Rigger set his own costume ablaze, but in the ensuing battle the Firebug accidentally fell from the building roof, his costume's napalm tanks exploding long before he could reach the ground. However he miraculously survived this encounter, and took on a mission from the Calculator which brought him into conflict with the Hero's Hotline while attempting to invade there base, but was once again defeated and was imprisoned in BlackGate prison, shortly afterwards he escaped. Following his escape he attempted to prove his superiority over fellow arsonist Firefly, but was believed killed once again. He would once again turn up alive when Gotham's Major Crimes unit was investigating a rash of Firebug attacks through out the city, invaded his apartment causing Joe to leap from his room and break several bones in the process. Once he recovered he revealed to the officers that because of the suit and frequent fires he now covered in scars, so he sold it on a anonymous auction online only meeting with the buyer once to show him how to operate it, and identifying the man when Gotham P.D. tricked him into coming into the station.
At first Harlan Combs is just a suspect in a young Gotham girl's murderer, which draws the interest of the Major Crimes unit for Gotham.Eventually with the the aid of the original Firebug he is identified as the purchaser of his suit, and the culprit behind the new Firebug's arson attacks, having murdered the girl by striking her in the head with one of his anti-gravity tanks after she found his costume in a hidden compartment in his closet. He is eventually arrested following his wife confessing to his crimes.
An unnamed character using the Firebug persona won the costume and the name from an Internet auction. After taking on the Firebug name, he enters the costume business. He later appeared in a flashback revealing that he teamed up with Mr. Freeze but was defeated by the team of Batman and Harvey Dent prior to Batman leaving for a year.
New 52 Batgirl
Joe Rigger is alive and continuing his arsonist campaigns.
In the future, Gotham is terrorized by the Firebug but it has not been determined if its a new Firebug or if Joseph Rigger still has a little spark of fiery determination in him.
In other media
Firebug appears in Batman NES as the second to last boss.