  We construct and analyze nonsupersymmetric SO(10) standard model extensions
which explain dark matter (DM) through the fermionic Higgs portal. In these
SO(10)-based models the DM particle is naturally stable since a $Z_2$ discrete
symmetry, the matter parity, is left at the end of the symmetry breaking chain
to the standard model. Potentially realistic models contain the $\bf{10}$ and
$\bf{45}$ fermionic representations from which a neutralino-like mass matrix
with arbitrary mixings can be obtained. Two different SO(10) breaking chains
will be analyzed in light of gauge coupling unification: the standard path
$\text{SU}(5)\times U(1)_{X}$ and the left-right symmetry intermediate chain.
The former opens the possibility of a split supersymmetric-like spectrum with
an additional (inert) scalar doublet, while the later requires additional
exotic scalar representations associated to the breaking of the left-right
symmetry.
