Clontarf Castle is a much-modernised castle, dating to 1837, in Clontarf, Dublin, Ireland, an area famous as a key location of the Battle of Clontarf in 1014. There has been a castle on the site since 1172. In modern times, it has functioned as a bar, cabaret venue, and hotel.

Clontarf is an affluent coastal suburb on the Northside of Dublin in the city's Dublin 3 postal district. Historically, there were two centres of population, one on the coast towards the city, and the fishing village of Clontarf Sheds, further north on the coast at what is now Vernon Avenue. Clontarf has a range of retail businesses in several locations, mainly centred on Vernon Avenue. It adjoins Fairview, Marino, Killester and Raheny. Clontarf is in the jurisdiction of Dublin City Council.