We show that the dark matter (DM) could be a light composite scalar η, emerging from a TeV-scale strongly-coupled sector as a pseudo Nambu-Goldstone boson (pNGB). Such state arises naturally in scenarios where the Higgs is also a composite pNGB, as in O(6)/O(5) models, which are particularly predictive, since the low-energy interactions of η are determined by symmetry considerations. We identify the region of parameters where η has the required DM relic density, satisfying at the same time the constraints from Higgs searches at the LHC, as well as DM direct searches. Compositeness, in addition to justify the lightness of the scalars, can enhance the DM scattering rates and lead to an excellent discovery prospect for the near future. For a Higgs mass m h 125 GeV and a pNGB characteristic scale f 1 TeV, we find that the DM mass is either m η 50−70 GeV, with DM annihilations driven by the Higgs resonance, or in the range 100−500 GeV, where the DM derivative interaction with the Higgs becomes dominant. In the former case the invisible Higgs decay to two DM particles could weaken the LHC Higgs signal.

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In the absence of low energy supersymmetry, we show that (a) the dark matter particle alone at the TeV scale can improve gauge coupling unification, raising the unification scale up to the lower bound imposed by proton decay, and (b) the dark matter stability can automatically follow from the grand unification symmetry. Within reasonably simple unified models, a unique candidate satisfying these two properties is singled out: a fermion isotriplet with zero hypercharge, member of a 45 (or larger) representation of SO(10). We discuss the phenomenological signatures of this TeV scale fermion, which can be tested in direct and indirect future dark matter searches. The proton decay rate into e + π 0 is predicted close to the present bound.