Searches for dark matter and extra dimensions with the ATLAS detector

Different approaches to finding evidence for dark matter at the LHC are presented. These include searches for events with large missing transverse momentum and a single jet, photon or W/Z boson, as well as events with long-lived particles resulting in displaced hadronic vertices or lepton-jet signatures. Those studies are also sensitive to the presence of extra spatial dimensions. Additional searches for classical and quantum black holes are also described.