When you go to the panel for spawning aggressive NPCs, you find a "Shadow Mutant"

You spawned her and she looked at you with her white-red eyes. Unlike the usual "Shadow Mutant", it looked as female version of the character. Black skin, black tentacles behind, dark smoke around and chubby body with HUGE FREAKIN CHEST.

Literally a second after discovering your presence, she rushed after you at great speed, shouting

"ROOOOAR!!!" She came running to you with hungry eyes.