  In [BFMT17] we introduced orbital degeneracy loci as generalizations of
degeneracy loci of morphisms between vector bundles. Orbital degeneracy loci
can be constructed from any stable subvariety of a representation of an
algebraic group. In this paper we show that their canonical bundles can be
conveniently controlled in the case where the affine coordinate ring of the
subvariety is Gorenstein. We then study in a systematic way the subvarieties
obtained as orbit closures in representations with finitely many orbits, and we
determine the canonical bundles of the corresponding orbital degeneracy loci in
the Gorenstein cases. Applications are given to the construction of low
dimensional varieties with negative or trivial canonical bundle.
