  We construct an explicit scenario whereby the same material driving inflation
in the early Universe can comprise dark matter in the present Universe, using a
simple quadratic potential. Following inflation and preheating, the density of
inflaton/dark matter particles is reduced to the observed level by a period of
thermal inflation, of a duration already invoked in the literature for other
reasons. Within the context of the string landscape, one can further argue for
a non-zero vacuum energy of this field, thus unifying inflation, dark matter
and dark energy into a single fundamental field.
