B.J. Blazkowicz is a Doom Marine in Doom RPG, possibly the name of the Marine, the player character in the game. You find the name mentioned a log addressed to B.J. Blazkowicz discussing a hidden secret room containing a shotgun for the Marine to find.It is stated that the official doom marine have no name because he represents the player.The name B.J. Blazkowicz could be an ingame joke too.