Wraith

Wraiths are a creature (or creatures) seen in Doom 3 and Doom (2016). Albeit in two drastically different mutated forms.

Background
Wraiths were once a great space faring race that travelled through the stars.

They are susceptiable to exposure to Hell's energy which in copious amounts will drastically change the visual and internal structure of beings.

Their original pre-Demonic forms are not known.

Doom 64
Wraiths are another name for the Nightmare Imps along with "Shadow Warriors".