Measurements of single top-quark production in proton-proton collisions are presented based on the 8 TeV and 13 TeV ATLAS datasets. In the leading order process, a W boson is exchanged in the t-channel. The cross-section for the production of single top-quarks and single anti-top-quarks, their ratio, as well as differential cross-section measurements are also reported. These analyses include limits on anomalous contributions to the Wtb vertex and measurement of the top quark polarization. Measurements of the inclusive and differential cross-sections for the production of a single top quark in association with a W boson, the second largest single-top production mode, are also presented. Finally, evidence for s-channel single-top production in the 8 TeV ATLAS dataset is presented. All measurements are compared to state-of-the-art theoretical calculations.