Beyond Standard Model searches with top quark at ATLAS

At the LHC, the top quark is expected to be a huge and clean signal. With about eight millions of expected top pairs and three millions of single top events produced per year in the low luminosity runs, and with a low level of backgrounds, the LHC will open a new opportunity for precision measurements of the top quark properties and for exotic topology searches involving top quarks. As the ATLAS discovery potential on new physics with top quark is being assessed with many analyses, this article focuses on two particular topics: heavy neutral resonances and charged Higgs boson searches with top quarks. The analyses and the ATLAS expectations are described.