Angra Mainyu
Unlike Mazdean Zoroastrianism, Zurvanism considered Ahura Mazda not the transcendental Creator, but one of two equal-but-opposite divinities under the supremacy of Zurvan. The central Zurvanite belief made Ahura Mazda (Middle Persian: Ohrmuzd) and Angra Mainyu (Ahriman) twin brothers that had co-existed for all time.