  The LHC did not discover new particles beyond the Standard Model Higgs boson
at 7 and 8 TeV, or in the first data samples at 13 TeV. However, the
complementary nature of physics with $e^+e^-$ collisions still offers many
interesting scenarios in which new particles can be discovered at the ILC.
These scenarios take advantage of the capability of $e^+e^-$ collisions to
observe particles with missing energy and small mass differences, to observe
mono-photon events with precisely controlled backgrounds, and to observe the
full range of exotic decay modes of the Higgs boson. The searches that an
$e^+e^-$ collider makes possible are particularly important for models of dark
matter involving a dark sector with particles above the modest energy reach of
fixed-target experiments. In this talk, we will review the opportunities that
the ILC offers for new particle discovery.
