Zarathustra is famously invoked by Nietzsche to sweep away a univocal theology - Western Christian monotheism; in the history of religions Zarathustra is famous as the founder of Zorastrianism; this a theology of the Two rather than a One; postulating two independent powers: asa (truth) and druj (lies).
One notes a similar doctrine of duality advocated by the pre-socratic Empedocles of Philia (love) and niekos (strife); and one can trace the voyage of this duality to contemporary times:
Nothing & Being - by Sartre
Being & Time - by Heidegger
Gravity & Grace - by Simone Weil
Being & Event - by Badiou
though probably not (the two concepts are not 'oppositional' in some sense, as they are in the others mentioned; ie Time erases Being; though Heidegger does place Time in essential relation to Being too).
Should Zarathustra be considered an emblematic figure in the history of Western philosophy, despite his indubitably Eastern origin? Raphael, for example thought so - he placed Zarathustra in his fresco The School of Athens in the Apostolic Palace in the Vatican; which rather suggests that there was a current of thought in the Renaissance that positioned him as such.