Doctor Phosphorus

History
A crack in a reactor core caused Alex Sartorius to get "five million slivers of (radioactive) red-hot sand" into his body. Burning forever, he started a quest for revenge against the people he blamed for his terrible fate.

During the Underworld Unleashed storyline, he was one of many villains to sell his soul to the demon Neron. In exchange for his soul, he was granted greater power and more control; for example, he could now wear normal clothing without it bursting into flame.

In James Robinson's series Starman he was initially hired by the Mist to kill the original Starman, Ted Knight, but was defeated by the retired hero. However, they would face each other a second time; this time, Phosphorus had given Knight a significant dose of radiation, which gave him terminal cancer. In a third and final confrontation, Knight was determined to ensure that Phosphorus would harm no one else. During the battle, he used his cosmic rod to tear the pavement from beneath Phosphorus and drive him into the earth, apparently killing him.

Phosphorus returned in Detective Comics #825, where he was being held in Cadmus Research laboratories. When one of the scientists examining him said he heard Sartorius had died, the other replied, "From being crushed? Hardly. Everything human in Sartorius was consumed by fire long ago. We believe his powers manifested a fusion reaction that completely sublimated his central nervous system--creating functional facsimiles of his heart, his lungs, his kidneys--all working in concert to produce a near-endless supply of clean energy."

Phosphorus was able to escape from Cadmus, and once again sought revenge on the people who had caused his decision. He was defeated by Batman during an attack on Rupert Thorne, and he was imprisoned in Arkham Asylum.

Powers and abilities
Doctor Phosphorus has burning skin, toxic emissions, and can manipulate radiation. When he sold his soul to Neron, Doctor Phosphorus was granted better control of his powers with more control of it so his clothes won't burn off him.

Depictions in other media
The character Blight from the animated series Batman Beyond has a design that strongly resembles Doctor Phosphorus.

In The Batman, Firefly's mutation from the Phosphorus Isotope causes him to become Phosphorus, who is somewhat based on Doctor Phosphorus. He has the same powers of Doctor Phosphorus, but he burns orange flame instead of white.