  We propose that the SU(2) x SU(2) x U(1) (aka G221) models could provide us a
750 GeV scalar resonance that may account for the diphoton excess observed at
the LHC while satisfying present collider constraints. The neutral component of
the $SU(2)_R$ scalar multiplet can be identified as the 750 GeV scalar. In the
lepto-phobic and fermio-phobic G221 models the new charged gauge boson W' could
be light, and we find that the diphoton decay width could be dominated by the
loop contribution from the $W'$. To initiate gluon fusion production, it is
necessary to extend the G221 symmetry to the Pati-Salam and SO(10) symmetry. We
investigate the possibilities that the light colored scalars or vectorlike
fermions survive in the SO(10) theory and provide large gluon fusion rate for
the diphoton signature. It is possible to test the G221 interpretation by
direct searches of W' using the multi-gauge boson production channel at the Run
2 LHC.
