Skull Face is an antagonist in Kojima Production's Metal Gear Solid V series, Ground Zeroes and The Phantom Pain. His face is horribly scarred beyond recognition, and his past and identity are shrouded in mystery.
However, a hidden cassette tape in Ground Zeroes features a lengthy speech from Skull Face (as he tortures an unnamed individual) where he details what he says are the events that led to his face being disfigured. Supposedly, he was badly burned by rapeseed oil while a building he was in was being burned to the ground for manufacturing guns secretly. However, given Skull Face's deceitful nature, it is impossible to know if he was being truthful, or lying in the game.