  Are black holes elementary particles? Are they fermions or bosons? We
investigate the remarkable possibility that quantum black holes are the
smallest and heaviest elementary particles. We are able to construct various
fundamental quantum black holes: the spin-0, spin 1/2, spin-1, and the
Planck-charge cases, using the results in general relativity. Quantum black
holes in the neighborhood of the Galaxy could resolve the paradox posed by the
Greisen-Zatsepin-Kuzmin limit on the energy of cosmic rays from distant
sources. They could also play a role as dark matter in cosmology.
