  We study the effective field theory obtained by extending the Standard Model
field content with two singlets: a 750 GeV (pseudo-)scalar and a stable
fermion. Accounting for collider productions initiated by both gluon and photon
fusion, we investigate where the theory is consistent with both the LHC
diphoton excess and bounds from Run 1. We analyze dark matter phenomenology in
such regions, including relic density constraints as well as collider, direct,
and indirect bounds. Scalar portal dark matter models are very close to limits
from direct detection and mono-jet searches if gluon fusion dominates, and not
constrained at all otherwise. Pseudo-scalar models are challenged by photon
line limits and mono-jet searches in most of the parameter space.
