Doom's Doomguy is related to Wolfenstein's B.J. Blazkowicz through one of the most bizarre character connections, that of Commander Keen. Commander Keen from the Commander Keen series is the grandson of B.J. Blazkowicz. Then Commander Keen had a son which the world has deemed 'Doomguy", which makes Wolfenstein's B.J. Blazkowicz the Great Grandfather of Doom's Doomguy.