Dark Lord

The Nameless One, also called the Dark Lord and the Lord of the Fourth Age, is the unseen ruler of Hell. His lieutenants are the Archdemons, who enforce his will unquestioningly.

History
The Nameless One was created as Davoth, a Primeval created by the Father to watch over the realm of Jekkad. While benevolent by nature, he feared that one day his people would die off and leave him utterly alone and so influenced the people of Jekkad to seek immortality. The Father foresaw that Davoth's obsession would ultimately make him and Jekkad a threat to all existence, and so he sealed it away. Davoth became infuriated at the perceived betrayal and bent all of Jekkad to his will, causing it to become Hell. As he continued to conquer other worlds, the Father fought him and tore out his life sphere, preventing him from taking a physical form.

While the Nameless One has yet to appear directly, it is believed that he may have been the demonic voice that first contacted Olivia Pierce with the offer to ease her pain and is later heard threatening her over her failure to keep the Doom Slayer from being reawakened, and repeatedly urges the demons to oppose the Doom Slayer during various points in Doom (2016). In Doom Eternal, it is also stated that he was the one who negotiated Hell's alliance with the Maykrs.

During the events of The Ancient Gods, Part One, the Slayer retrieves the Dark Lord's life sphere and brings it to Urdak in order to force him to take a physical form- should he be killed, every demon outside of Hell itself will be immediately annihilated as their connection to reality is severed. Inexplicably, his new body is a perfect copy of the Slayer's own.