The presence of a non-baryonic dark matter (DM) component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model (SM) it could be produced at the LHC. The ATLAS experiment has developed a broad search program for DM candidates. The results of recent searches on 13 TeV pp data, their interplay and interpretation will be presented, including in particular the recent interpretation in the context of a 2HDM+pseudoscalar model. Prospects for HL-LHC will also be discussed.