Wraith/Doom (2016)

The Wraiths, otherwise known as The Elemental Wraiths or The Firstborns were godlike beings originally from the realm of Argent D'Nur. They were revered and worshiped by the Argenta, who formed the Night Sentinels to protect to them. In turn, the Wraiths empowered the Night Sentinels, making them nearly invincible against the demonic forces of Hell.

History
The Wraiths were the very first lifeforms to born on Argent D'Nur. According to the Ligra Sultagenta (Book of Kings), an immense shard of rock and metal known as the Cosmic Spear impacted Argent D'Nur, impaling through the planet. The impact opened the "Womb of the World" and released the Wraiths, who then brought life to the planet in what is known as the Wraithcall. Fierce beasts and an unforgiving biosphere rose from the Wraithcall in which the first of those were the Ancestrals, towering behemoths invigorated by the magic of the Wraiths who waged war with each other for years untold and destroying everything in their wake. The Wraithcall soon gave rise to the Argenta and the Wraiths gifted early man with magic and the knowledge to forge weapons to drive back the Ancestrals and claiming dominion over Argent D'Nur. The Argenta owed gratitude to the Wraiths and worshiped them as their gods, and forming the order of the Night Sentinels to protect the Wraiths and their civilization from outside threats.

During the Time of Grief, the Argenta shifted their worship of the Wraiths to the Maykrs after the divine-like advanced race allied with the Argenta by providing them advanced technology and safety from Argent D'Nur's harsh environment along with promises of "eternal peace" in Urdak. During the Unholy War against Hell, the Maykrs and the Order of the Deag discovered the potentials of combining the demons' Hell Essence and the Wraiths' powers to create Argent Energy, an extraordinary energy that could end or enhance life.

However, the Argenta soon came to learn about the Maykrs' unholy pact with the Dark Lord of Hell to harvest limitless Argent Energy by providing helping Hell with the process of harvesting other races and harvesting their life essence and further expand the dominion of Hell. The non-indoctrinated Argenta rejected their worship of the Maykrs and returned to the way of the Wraiths.

Fall of the Wraiths
A Night Sentinel, Commander Valen, lost his son in the war against Hell and was haunted by demonic visions of his son's tortured existence. Desperately wanting to free from his son from his torment, Valen was approached by the Hell Priest Deag Grav with promises of resurrecting his son for a price: the keys to the Sepulcher of Elements and opening the vault of the sleeping Wraiths. Valen relented and Hell's forces abducted the ancient creatures, transporting them to Hell where they are were cursed and subjugated, and were used to fuel The Well. The Argenta fell and the Night Sentinels were scattered across Hell and inevitably killed to the last man. As for Valen, who has since been condemned as the Betrayer, he only had his son resurrected in the form of a powerful demon, the Icon of Sin.

For the next three ages, until the fourth age the Wraiths were under Hell's corruption, the Wraiths were strung to sacrificial altars that siphoned their elemental energy into powering The Well, giving demon-kind unlimited energy to use in their conquests.

Freedom
The Wraith were eventually freed by the Doom Slayer; the Slayer traveled to the ruins of Argent D'Nur and using The Crucible he breaks the Wraiths free from their bondage, and subsequently depriving The Well from Hell

Description
Their general appearance prior to their sighting in Doom (2016) is unknown, as it has been shown that exposure to Hell's energy in copious amounts will drastically change the visual and internal structure of beings.

The Wraiths had great energy within them, clearly shown as they could have powered the Well for so long (centuries or thousands of years, although the time frame is unknown) and it is presumed had they not been freed they would have been powering demonkind for many years more to come.