Amaru (Natalie Martinez) is the true main villainess from Season Three of From Dusk Till Dawn: The Series.
Amaru is an evil ancient Queen of the Underworld, and in the season opener, "Head Games," she took control of Kate Fuller, after she was presumed dead in the end of Season Two. While in Kate's body, Amaru went on her quest to take down the remaining Lords, while also trying to regain her true form. Among her many battles was against Santanico Pandemonium, featured in the episode, "La Reina."
Amaru is finally freed from Kate's body in the season's penultimate episode, "Matanzas," after performing a ritual that included the ashes of the Nine Lords. Once her true physical form is revealed, Amaru informed the people at the church to bow their heads.