The production of ttZ serves as an important probe of the coupling of top quarks to Z bosons. Modifications to the ttZ vertex by physics beyond the Standard Model would have an effect on the ttZ production rates. The first measurements of ttZ production were performed in 8 TeV data by the ATLAS and CMS experiments at the LHC. At 13 TeV collision energy, the production rate of ttZ increases by almost a factor of four and the effects of new physics, if present, should become more prominent. The first measurement by ATLAS of ttZ production at 13 TeV is presented here, with a focus placed on the selection region that requires three charged leptons. This signature constitutes a compromise between a higher branching ratio for hadronic top quark decay chains and the better separation from background of the leptonic top quark decays. Moreover, the ttW process is measured, using final states that contain either three charged leptons or two muons of the same charge. The first observation of ttW was performed by ATLAS using 8 TeV data. Measuring this process can probe several different models for physics beyond the Standard Model.