Search for t#bar{t} resonances and vector-like quarks with the ATLAS detector

In the present talk the search for new resonances decaying to tt resonances, as well as the search for new vector-like quarks will be presented. The search is performed with the ATLAS experiment at the LHC using proton-proton collision data. The current status of the ATLAS searches in different topolo- gies will be reviewed, addressing the used analysis techniques, in particular the selection criteria, the background modelling and the related experimen- tal uncertainties. The phenomenological implications of the obtained results will also be discussed.