The character will be played by Andrew Dunbar, Firefly is described as a firefighter named Garfield Lynns is horribly burned on the job and hasn't recovered physically nor emotionally, which prompts him to transform into the villain Firefly.
Firefly will make his appearance on the show sometime around Episode 10.
Source : TVGuide
Are you excited with this new character additions? Do these spoiler tidbits make you excited for the rest of the season?