The results of searches for new phenomena in events with zero leptons/one lepton/two leptons (electrons or muons), jets, and missing transverse momentum are reported, using 13.3fb-1 of integrated luminosity from LHC pp collisions at √s=13TeV collected by the ATLAS detector. A range of scenarios with different mass splitings between the stop, the lightest chargino and the lightest neutralino are considered. The analyses also targets the production of dark matter in association with a pair of top quarks using the same final states. The largest deviation from the Standard Model prediction is found in one signal selection, corresponding to a local significance of 3.3 standard deviations. For the other selections, no large excess above the Standard Model expectation is observed, and exclusion limits at 95% confidence level are derived for the different models.