  We propose a minimal model to simultaneously account for a realistic neutrino
spectrum through a type-I seesaw mechanism and a viable dark matter relic
density. The model is an extension of the Littlest Seesaw model in which the
two right-handed neutrinos of the model are coupled to a $Z_2$-odd dark sector
via right-handed neutrino portal couplings. In this model, a highly constrained
and direct link between dark matter and neutrino physics is achieved by
considering the freeze-in production mechanism of dark matter. We show that the
neutrino Yukawa couplings which describe neutrino mass and mixing may also play
a dominant role in the dark matter production. We investigate the allowed
regions in the parameter space of the model that provide the correct neutrino
masses and mixing and simultaneously give the correct dark matter relic
abundance. In certain cases the right-handed neutrino mass may be arbitrarily
large, for example in the range $10^{10}-10^{11}$ GeV required for vanilla
leptogenesis, with a successful relic density arising from frozen-in dark
matter particles with masses around this scale, which we refer to as
"fimpzillas".
