Dr. Henry Hewitt, nicknamed Tokamak by Cisco Ramon, is a meta-human who was affected by the S.T.A.R. Labs particle accelerator explosion and gained the ability to absorb and generate fire-like energy, thus having similar abilities to Firestorm. His powers didn't surface, however, until an unsuccessful attempt by Team Flash to fuse him with a dying Martin Stein through the use of Firestorm Matrix. Following said attempt, Henry turned into a raging, vindictive meta-human with the ability to absorb and generate deadly energy.