Heinrich K%C3%B6selitz
Johann Heinrich Kselitz was a German author and composer. He is known for his longtime friendship with Friedrich Nietzsche, who gave him the pseudonym Peter Gast.
Kselitz was born in Annaberg, Saxony to Gustav Hermann Kselitz , the vice mayor , and his wife Caroline , a native of Vienna. His younger brother was the painter Rudolf Kselitz.
Source: Wikipedia