A photino is a subatomic particle, the fermion WIMP superpartner of the photon predicted by supersymmetry. Photinos have a lepton number 0, baryon number 0, and spin 1/2. With an R-parity of -1 it is a possible candidate for dark matter. It mixes with the superpartners of the Z boson (zino) and the neutral higgs (higgsino) to the neutralino.