Cecil L'Ively is a man with pyrokinesis, or the ability to control fire. He used this ability to murder several important dignitaries in England before doing the same in the United States. He was ultimately defeated by Agents Mulder and Scully with assistance from Phoebe Green.
During the episode Scully finds out that a person in the UK with this name has died two times under hot and strange circumstances. The first person was a kid that apparently was burned alive during a satanic ritual sometime in the '60s. The second person died in 1971 in a terrible fire. In the end of the episode L'Ively spontaneously catches fire and recovers "miraculously" fast in a military hospital. On asked how they can help him further, L'Ively responds to the nurse that he would die for a cigarette.