  We consider the possibility of interpreting the recently reported diphoton
excess at 750 GeV as a spin-two massive particle (such as a Kaluza-Klein
graviton in warped extra-dimensions) which serves as a mediator to Dark Matter
via its gravitational couplings to the dark sector and to the Standard Model
(SM). We model non-universal couplings of the resonance to gauge bosons in the
SM and to Dark Matter as a function on their localization in the extra
dimension. We find that scalar, fermion or vector dark matter can saturate the
dark matter relic density by the annihilation of dark matter into a pair of the
SM particles or heavy resonances, in agreement with the diphoton resonance
signal strength. We check the compatibility of our hypothesis with other
searches for the KK graviton. We show that the invisible decay rate of the
resonance into a pair of dark matter is subdominant in the region of the
correct relic density, hence leading to no constraints from the mono-jet bound
at 8 TeV via the gluon coupling. We also discuss the kinematic features of the
decay products of a KK graviton to distinguish the KK graviton from the SM
backgrounds or a scalar particle interpretation of the diphoton resonance.
