These proceedings summarise recent searches for dark sector mediators, in particular dark photons, using $\sqrt{s}=13$ TeV proton-proton collision data collected by the ATLAS and CMS experiments at the Large Hadron Collider (LHC). The searches target a wide range of dark photon masses, from 0.2 to 200 GeV, as well as massless dark photons, and exploit a variety of experimental signatures. The first collider constraints for scalar dark energy are also presented.