Clontarf is a suburb of Sydney, Australia. Situated on the southern extremity of the Northern Beaches, it is an affluent area containing mansions and expensive homes. Clontarf has a sub-tropical climate and river views.

Close to the tourist precinct of Manly, Clontarf is more affluent than some areas to the immediate north. It is serviced by Metroad 10 (Pittwater Road), but the only public transport is by bus, along the Spit Road. One landmark is the Spit Bridge, which opens periodically throughout the day. The presence of bridge on the Spit Road is often seen as bane of the Northern Beaches by residents; traffic delays on the Spit Road can be extreme (it has been compared with an 100 car pileup on an Los Angeles freeway in rush hour).