Earth

Earth is the homeworld of the human race. It is the primary setting for Doom II and Doom Eternal, and is referenced heavily in Doom 3 and Doom (2016). It also briefly appears in Doom and Doom: Annihilation.

Doom/Thy Flesh Consumed
Doom's original ending and follow up Thy Flesh Consumed take place upon Doom Guy's return to Earth via a teleporter (at the end of Inferno), where he discovers the remains of his pet rabbit Daisy outside of his home city that is now overrun by demons. He fights his way through his hometown, to stop the initial invasion by Hell, setting up Earth's total invasion in Doom II.

Doom II
Earth is where most of Doom II takes place. Immediately following the events of the previous game, Earth has been invaded by the forces of Hell and a large proportion of the human population are killed. The player, who has traveled back to Earth by drop pod after the Hell invasion of Mars, battles the demon forces in order to allow the survivors to escape the ruined planet. At the end of the game, the invasion is defeated, and the survivors are left to presumably resettle and start rebuilding the planet.

Doom 3
In Doom 3, Earth is never seen in the game itself, but is mentioned multiple times as being the center of human civilization, as well as being the ultimate target of Dr. Malcolm Betruger and the demon forces. It is hinted that the ancient Martians may have fled to Earth after the devastating war with Hell, and that humans may be their descendants. It is also mentioned that at some point in the past, the demons were actually on Earth but were defeated and driven into Hell, hence their desire to return and retake the planet.

Doom II RPG
The middle of Doom II RPG is set on Earth, in the East Coast UAC Facility. The three main characters of the game are teleported there after working their way through the Moon's Lunar Outpost.

Doom (2016)
Earth at the time of Doom (2016) is heavily populated and prone to energy shortages. Thus the discovery of Argent Energy on Mars was a huge boon, allowing nearly limitless energy potential for humanity. This technological breakthrough was spearheaded by the UAC, a mega-corporation led by Dr. Samuel Hayden to mine Argent Energy as well as research archaeological sites in the dimensions beyond.

Doom Eternal
By the events of Doom Eternal, Earth is overrun by the forces of Hell. Over 60% of humanity is mentioned to have been killed or consumed by Hell's legions, with many major cities having been destroyed in the process and Earth's environment and atmosphere becoming more inhospitable due to demonic corruption. The remnants of humanity have either fled the planet, or reside in massive fortress cities under the jurisdiction of the Armored Response Coalition. The damage to Earth does not limit itself to the planet's surface--the moon has been partially destroyed, with portions of it forming a ring of debris around Earth.

The Hell invasion soon ended with deaths of the Hell Priests and Icon of Sin at the hands of the Doom Slayer, causing all demons to retreat from Earth.