Host City: Melbourne, AustraliaBoycotting Countries: China, Egypt, Iraq, Lebanon, the Netherlands, Spain and Switzerland

Australia’s first hosting stint also marked the first Olympic boycott, with numerous countries withdrawing for a variety of political reasons. Less than a month before the opening ceremony, the Soviet Union invaded Hungary to stop the Hungarian Revolution against the Communist regime; in protest, the Netherlands, Spain and Switzerland all refused to participate. Meanwhile, the People’s Republic of China also withdrew—and would not return until the 1980 Winter Games—because Taiwan, which it considers a breakaway province, was allowed to participate as a separate country. And, finally, Egypt, Iraq and Lebanon boycotted the 1956 Olympics due to the Suez Canal Crisis following the British-Israel-French invasion of Egypt to control the waterway.

Despite other countries’ boycott against the Soviets, Hungary competed in the Olympics, and its athletes received support from fans, while Soviet athletes faced boos. A violent water polo match between the two teams left one Hungarian player bleeding from the head and led to a fight among spectators and athletes. Hungary, up 4-0 at the start of the brawl, was named the winner and the team eventually won the gold medal. The Soviets, for their part, went on to win the most medals for the first time.

In a show of peace, the Olympic athletes, for the first time, marched into the closing ceremony mixed together, rather than as separate nations—a tradition that continues today.

Host City: Tokyo, JapanBoycotting Countries: China, North Korea and Indonesia

China, North Korea and Indonesia chose to boycott the first Games held in an Asian country after the International Olympic Committee (IOC) declared it would disqualify athletes who competed in the 1963 Jakarta-held Games of the New Emerging Forces, created as an alternative multinational amateur competition. The boycotting countries sent many of their top athletes to the Jakarta games.

It was the first year South Africa was banned from participating in the Olympics because of apartheid, a ban that continued until 1992.

Host City: Montreal, CanadaBoycotting Countries: More than 20 mostly African countries and Taiwan

When New Zealand’s national rugby team defied an international sports embargo against South Africa and toured the apartheid nation earlier in the year, 28 African nations—comprising most of the continent—declared a boycott of the Olympics, which was allowing New Zealand to participate. Led by Tanzania, the boycott involved more than 400 athletes. In a separate action, Taiwan withdrew from the Games when Canada refused to let its team compete as the Republic of China.

The boycott led to hotel and ticket refunds totaling $1 million Canadian dollars. It especially affected several track and field events, where nations such as Kenya and Tanzania were frequent medal winners.

Host City: Moscow, RussiaBoycotting Countries: 65 countries, led by the United States

Protesting the December 27, 1979, Soviet invasion of Afghanistan, more than 60 nations refused to compete in the Moscow-held games. Led by the U.S. and President Jimmy Carter, the boycott included Canada, Israel, Japan, China and West Germany, as well as most Islamic nations. Afghani athletes, notably, competed in the Games. Some countries did not forbid athletes from competing as individuals under the Olympic flag, but American athletes attempting to compete faced losing their passports. A group of American athletes sued the U.S. Olympic Committee to participate but lost the case. The boycott resulted in just 80 countries competing in the Olympics, the fewest since 1956.

Carter enlisted boxing star Muhammad Ali to campaign across Africa to recruit countries to join the boycott. However, Ali reversed course while on the tour, facing criticism for being a White House puppet. The boycott did little to end the Soviet-Afghan War, which raged on until 1989. And, with the U.S. and other powerhouses out of the competition, the Soviets won 195 medals, an Olympic record that still stands.

Host City: Los Angeles, United StatesBoycotting Countries: 14 countries, led by the Soviet Union

In retaliation for the U.S.-led boycott of the Moscow Games four years earlier, 14 nations, led by the Soviet Union and including East Germany, boycotted the Los Angeles-held Olympics. Joined by most of the Eastern Bloc nations, the Soviets said they feared physical attacks and protests on American soil. "Chauvinistic sentiments and anti-Soviet hysteria are being whipped up in this country,” a government statement read.

Despite the boycott, 140 nations competed in the Games, an Olympic record. And with the Soviets out of the running, the U.S. easily won the medal count, including a record 83 gold medals. China, in its first Summer Games since 1952, scored 31 total medals. American track phenoms Carl Lewis and Joan Benoit, along with Mary Lou Retton, the first American gymnast to win the gold for all-around, became instant stars. And the Games were considered a huge financial success, with almost double the ticket sales of Montreal and earning the title as the most-seen event in TV history.

Host City: Seoul, South KoreaBoycotting Countries: Cuba, Ethiopia, Nicaragua and North Korea

Angered over not being allowed to co-host the Games with South Korea, North Korea refused to attend the 1988 event in neighboring Seoul. The Soviet Union, meanwhile, accepted the IOC's invitation to compete, along with China and Eastern Bloc nations, leaving just Cuba, Ethiopia and Nicaragua joining North Korea in the boycott. “To have the Olympics in Seoul would be like having them at the Guantanamo naval base occupied by the United States," Cuba President Fidel Castro told NBC News at the time. "I wonder that, if Socialist countries refused to go to (the 1984 Olympics in) Los Angeles for security reasons, if really there is more security in Seoul than in Los Angeles.”

The boycotts couldn't outshine the fact that the 1988 Olympics, the last Games of the Cold War era, set a new record for the number of nations (159) and athletes (8,000) participating.

Scandals tarnished the Seoul Games, including reports of residents being forced from their homes and homeless people being detained at facilities in preparation for the Games. Canadian sprinter Ben Johnson made global headlines when he was stripped of his world-record-setting 100-meter victory after testing positive for steroids, and controversial boxing calls that went against South Korean athletes caused outrage.

North and South Korean leaders met following the events, and agreed to send a combined team to the 2021 Tokyo Summer Games. However, North Korea announced in April 2021 that it would not participate because of the coronavirus pandemic.