This is Tyhjyys.
Her realm is the eternal darkness of the void. She will haunt you in your nightmares, and nothing can stop her, until the day you wake up and she is there (ever experienced sleep paralysis? She is the terrifying presence you feel). If you say her name thrice in a dark room in front of a mirror, she will appear before you and kill everyone in the house.
Created her while listening to Aqua by Edgar Froese.