Gamma Rays from Dark Matter

I give a brief review of high energy gamma-ray signatures of dark matter. The decay of massiveX-particles and subsequent hadronization have been suggested as the origin of the highest energy cosmic rays. Propagation over cosmological distances to Earth (as would be the case in some topological defect origin models for the Xparticles) results in potentially observable gamma-ray fluxes at GeV energies. Massive relic particles on the other hand, would cluster in galaxy halos, including that of our Galaxy, and may give rise to anisotropic gamma ray and cosmic ray signals at ultra high energies. Future observations above 100 Gev of gamma rays due to WIMP annihilation in the halo of the Galaxy may be used to place constraints on supersymmetry parameter space.