Seth

"Though for some of you, the deepest pit of hell has opened to swallow you whole. Don't resist it old friends"

-Seth during the Hellfire ending

Description
Seth serves as the guide to the player character. It is unknown who he works for, but is assumed to be a part of the Nevada Raiders.

In-Game
Seth is always guiding the player throughout the Nevada Primary Research Facility. His appearance is revealed in the end.