  The current status of origin of Ultra High Energy Cosmic Rays (UHECR) is
reviewed, with emphasis given to elementary particle solutions to UHECR
problem, namely to Topological Defects and Super-Heavy Dark Matter (SHDM)
particles. The relic superheavy particles are very efficiently produced at
inflation. Being protected by gauge discrete symmetries, they can be long
lived. They are clustering in the Galactic halo, producing thus UHECR without
Greisen-Zatsepin-Kuzmin cutoff. Topological Defects can naturally produce
particles with energies as observed and much higher, but in most cases fail to
produce the observed fluxes. Cosmic necklaces, monopoles connected by strings
and vortons are identified as most plausible sources. The latter two of them
are also clustering in the halo and their observational predictions are
identical to those of SHDM particles.
