Samuel Hayden is a Century old Robot with the consciousness of an Angel. He's pretty radical when achieving his goals but pretty dismissive of everything else

VEGA is a Advanced AI made by the UAC, who follows Doom Slayers every word, not questioning anything, just obeying with professionalism

Erzebet is a Female Marauder who turned somewhat Human again after meeting the Slayer. She's not all demon, but still has the abilities of a Marauder.

The Doom Slayer is the one the Demons fear