Sentinel Prime

Sentinel Prime is the homeworld of the Night Sentinels and their greater race, referred to as the Argenta, and is a location and the eighth level in Doom Eternal.

Pre-release
Some early screenshots of Sentinel Prime showed Mars in the planet's sky, possibly indicating that it exists on Phobos or Deimos in an alternate dimension or within a different time frame. It is currently unknown if this persists in the final game.