Doom Slayer

The developers have originally stated that the protagonist has no canon name because he is a representation of the player.

Alias DOOM, Doom Marine, Doom Slayer, Hellwalker. Unchained Predator, Scourge of Hell, The Slayer, The Beast, DM1-5. Doomguy, The Outlander. Affiliation Night Sentinels (formerly) Earth UAC Marine Security (formerly) Race God / Eternal (empowered) Sex Male Eye color Blue (Doom) Brown (Eternal) Hair color Brown The demons first gave him the appellation "Doom Slayer" and also refer to him as the Unchained Predator, the Beast, and the Hellwalker. The UAC refers to him as DOOM Marine, or The Slayer. Before the character had any epithets in the story, he was most commonly called Doomguy in the fan community. This nickname is mentioned in Doom Eternal and used in his dialogue subtitles. He is intended to be the latest iteration and continuation of the classic DOOM Marine who is the protagonist for most of the series. According to Tom Hall and John Romero (who worked on the original Doom), the original iteration of the DOOM Marine was the grandson of Commander Keen and the great-great-grandson of William J. Blazkowicz. The Doom Slayer's Blazkowicz ancestry may or may not be canonical for the modern iteration. The Doom Marine was originally a human from Earth who served in the Marines and was dishonorably discharged due to assaulting his commanding officer after refusing to fire upon a crowd of unarmed civilians and was later transferred to the UAC Phobos base as security. The Marine soon found himself trying to prevent the demons of Hell from invading Earth. After having fought demonic hordes through Phobos, Deimos and Hell, he returned home to find Earth now overrun by demons. Among the billions of people killed were his family, including his pet rabbit Daisy, giving him further reason to pursue hunting the demons. He continued fighting the horde on Earth, before taking the fight to Hell once more.