Port Arthur is a small town and former convict settlement on the Tasman Peninsula, in Tasmania, Australia. It is one of Australia's most significant heritage areas and an open-air museum. The site forms part of the Australian Convict Sites, a World Heritage property consisting of eleven remnant penal sites originally built within the British Empire during the 18th and 19th centuries on fertile Australian coastal strips. Collectively, these sites, including Port Arthur, now represent, "the best surviving examples of large-scale convict transportation and the colonial expansion of European powers through the presence and labour of convicts."

Port Arthur is officially Tasmania's top tourist attraction. It is located approximately 60 kilometres (37 mi) south east of the state capital, Hobart. In 1996 it was the scene of the worst mass murder event in post-colonial Australian history.