  There are many reasons to believe the present mass density of the universe is
dominated by a weakly interacting massive particle (WIMP), a fossil relic of
the early universe. Theoretical ideas and experimental efforts have focused
mostly on production and detection of thermal relics, with mass typically in
the range a few GeV to a hundred GeV. Here, I will review scenarios for
production of nonthermal dark matter. Since the masses of the nonthermal WIMPS
are in the range 10^{12} to 10^{16} GeV, much larger than the mass of thermal
wimpy WIMPS, they may be referred to as WIMPZILLAS. In searches for dark matter
it may be well to remember that ``size does matter.''

High Energy Physics - Phenomenology;Astrophysics