Lisa Trevor (Various)
Grotesquely disfigured and with almost no recollection of her former self, Lisa Trevor has been subjected to a variety of horrific experiments for the last 20 years; her body is now little more than a living incubator for new prototype virus strains. She takes particular interest in attacking female researchers, perhaps mistaking them for her own mother, who lost her life in similar experiments.
Mutations due to virus infection can occasionally produce unexpected results. The Licker may be one of the more well-known examples, but Lisa Trevor, who endured not only mutation but was also the source of the G-Virus, is by far the most extreme case. It is unknown whether the virus was a result of the synthesis of two or more of the other pathogens she was administered with, or if it was created due to the influence of some other unknown factor she possessed. The G-Virus made her all but immortal, and this fact is reflected in-game. For those seeking more information, her fate is detailed in The Umbrella Chronicles.