Betrayer

"'Saving your people will not bring you peace, only makes the burden you carry worse.'- The Betrayer to the Doom Slayer."

The Betrayer, real name Nabad, is the former general of the Night Sentinels that committed treason against the realm to bring back his dead son. He is one of the supporting characters in Doom Eternal.

Background
The Betrayer used to one of the Generals of Night Sentinels who led countless battle against the force of hell. However, after his son perished in a battle, he betrayed his kin to bring back his son, leading to the fall of Argent'D Nur and his comrades being scattered in hell.

Doom Eternal
The Doom Slayer meets the Betrayer to retrieve the Celestial Locator to track down and kill all the Hell Priests to destabilize hell force on Earth.