  Decaying superheavy particles can be produced by Topological Defects or, in
case they are quasi-stable, as relics from the early Universe. The decays of
these particles can be the sources of observed Ultra High Energy Cosmic Rays
($E \sim 10^{10} - 10^{12} GeV$). The Topological Defects as the UHE CR sources
are critically reviewed and cosmic necklaces and monopole-antiminopole pairs
are identified as most plausible sources. The relic superheavy particles are
shown to be clustering in the halo and their decays produce UHE CR without GZK
cutoff. The Lightest Supersymmetric Particles with Ultra High Energies are
naturally produced in the cascades accompanying the decays of superheavy
particles. These particles are discussed as UHE carriers in the Universe.
