Wraith is a name applied to three distinct creatures in the Doom series.
"Wraith" is another name for the Nightmare Imp.
The Wraith is a humanoid demon with the ability to teleport and a focus on melee attacks with its bladed arms.
Doom 2016 & Eternal
The Wraiths were a powerful species of creatures native to Argent D'Nur with abilities the local humans regarded as magical. They were imprisoned in the Well following the Argenta civil war and tortured so their essence could be used in the production of Argent Energy.