Thus Spoke Zarathustra: A Book for All and None (German: Also sprach Zarathustra: Ein Buch für Alle und Keinen), also translated as Thus Spake Zarathustra, is a work of philosophical fiction written by German philosopher Friedrich Nietzsche and published in four volumes between 1883 and 1885. The protagonist is nominally the historical Zarathustra, more commonly called Zoroaster in the West.
Much of the book consists of discourses by Zarathustra on a wide variety of subjects, most of which end with the refrain "thus spoke Zarathustra". The character of Zarathustra first appeared in Nietzsche's earlier book The Gay Science (at §342, which closely resembles §1 of "Zarathustra's Prologue" in Thus Spoke Zarathustra).