The brilliant scientist
Alexia Ashford who created the T-Veronica virus. She has been hibernating for the past 15 years with the virus inside of her body maturing to create what she believes to be the ultimate creation. Her first mutation removes her human appearance and trades it for a green-skinned humanoid with increased strength and agility, as well as being able to conjure up immense heat from her fingers that she can form into projectiles.
In your first battle with her it is strongly advisable to keep as far away as possible from her, as getting close would give her the opportunity to grab hold of you, which almost always results in an instant death. She will try to force you into a fixed spot with her lines of flame she produces, but try not to get cornered. Try to finish this battle as quickly as possible, as it is one of the most dangerous battles of the entire game.