The 1956 Summer Olympics, officially known as the Games of the XVI Olympiad, were an international multi-sport event held in Melbourne, Victoria, Australia, from 22 November to 8 December 1956, with the exception of the equestrian events, which were held in Stockholm, Sweden, in June 1956.

These Games were the first to be staged in the Southern Hemisphere and Oceania, as well as the first to be held outside Europe and North America. Melbourne is the most southerly city ever to host the Olympics. Due to the Southern Hemisphere's seasons being different from those in the Northern Hemisphere, the 1956 Games did not take place at the usual time of year, because of the need to hold the events during the warmer weather of the host's spring/summer (which corresponds to the Northern Hemisphere's autumn/winter), resulting in the only summer games ever to be held in November and December. Australia did not host the Games again until 2000 in Sydney, New South Wales, and will host them again in 2032 in Brisbane, Queensland.

The Olympic equestrian events could not be held in Melbourne due to Australia's strict quarantine regulations, so they were held in Stockholm five months earlier. This was the second time the Olympics were not held entirely in one country, the first being the 1920 Summer Olympics in Antwerp, Belgium, with some events taking place in Ostend, Belgium and Amsterdam, Netherlands. Despite uncertainties and various complications encountered during the preparations, the 1956 Games went ahead in Melbourne as planned and turned out to be a success. Started during the 1956 Games was the "Parade of Athletes" at the closing ceremonies.

Eight teams boycotted the Games for various reasons. Four teams (Egypt, Iraq, Cambodia and Lebanon) boycotted in response to the Suez Crisis, in which Egypt was invaded by Israel, France and the United Kingdom. Three teams (the Netherlands, Spain and Switzerland) boycotted in response to the Soviet invasion of Hungary, and China's boycott was in response to the presence of the Republic of China.The Soviet Union won the most gold medals, and the most medals overall.

One of the most notable events of the games was a controversial water polo match between the Soviet Union and the defending champions, Hungary. The Soviet Union had recently suppressed an anti-communist revolution in Hungary and violence broke out between the teams during the match, resulting in numerous injuries. When Ervin Zdor suffered bleeding after being punched by Valentin Prokopov, spectators attempted to join the violence, but they were blocked by police. The match was cancelled, with Hungary being declared the winner because they were in the lead.

The "Blood in the Water" match (Hungarian: melbourne-i vérfürdő lit. Blood bath of Melbourne; Russian: Кровь в бассейне, romanized: Krov' v basseyne, lit. 'Blood in the swimming pool') was a water polo match between Hungary and the USSR at the 1956 Melbourne Olympics. The match took place on 6 December 1956 against the background of the 1956 Hungarian Revolution, and saw Hungary defeat the USSR 4–0. The name was coined after Hungarian player Ervin Zádor emerged during the last two minutes with blood pouring from above his eye after being punched by Soviet player Valentin Prokopov.