  Searches for dark matter production at particle colliders are complementary
to direct-detection and indirect-detection experiments, and especially powerful
for small masses, $m_\chi<100$ GeV. An important collider dark matter signature
is due to the production of a pair of these invisible particles with the
initial-state radiation of a standard model particle. Currently, collider
searches use individual and nearly orthogonal final states to search for
initial-state jets, photons or massive gauge bosons. We combine these results
across final states and across experiments to give the strongest current
collider-based limits in the context of effective field theories, and map these
to limits on dark matter interactions with nuclei and to dark matter
self-annhiliation.
