Anton Heinrich Hermann Fassl (1876, Komotau - 1922, Manaos) was a German entomologist.
Fassl collected Lepidoptera and Coleoptera in Colombia (1907-1908), Brazil and Ecuador. He was sometime in Berlin, sometime at a dealership Naturhistorisches-Institut, 948 Zeidlerstrasse, Teplitz, Bohemia, Austria-Hungary (now Teplice, the Czech Republic). He supplied specimens to Ernst Hartert and Karl Jordan.