Ukraine competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's third consecutive appearance at the Summer Olympics in the post-Soviet era. The National Olympic Committee of Ukraine sent the nation's largest ever delegation to these Games. A total of 240 athletes, 125 men and 115 women, took part in 21 sports. Women's handball was the only team-based sport in which Ukraine had its representation at these Games for the first time. There was only a single competitor in modern pentathlon and taekwondo.
Cuba competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's seventeenth appearance in the Olympics, except for some editions. Cuban athletes did not attend in two Olympic Games, where they joined the Soviet and North Korean boycott. Cuban Olympic Committee sent the nation's smallest delegation to the Games since 1972. A total of 151 athletes, 97 men and 54 women, competed in 18 sports.
Bulgaria competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's seventeenth appearance at the Summer Olympics, except for three occasions, including the 1948 Summer Olympics in London due to the nation's role in World War II and 1984 Summer Olympics in Los Angeles because of the Soviet boycott. The Bulgarian Olympic Committee sent 95 athletes, 49 men and 46 women, to compete in 19 sports. Shooting champion and four-time Olympian Mariya Grozdeva became the nation's first ever female flag bearer in the opening ceremony.
Romania competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. Romanian athletes have competed at every Summer Olympic Games since its official debut in 1924, missing only two editions, including the 1948 Summer Olympics. The Romanian Olympic and Sports Committee sent the nation's smallest team to the Games since the 1988 Summer Olympics in Seoul. A total of 108 athletes, 50 men and 58 women, had competed in 16 different sports, most notably in artistic gymnastics and rowing. For the third time in Olympic history, Romania was again represented by more female than male athletes.
Thailand competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's thirteenth appearance at the Olympics, except the 1980 Summer Olympics in Moscow because of its partial support to the United States boycott.
Ireland competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's eighteenth appearance at the Summer Olympics.
Uzbekistan competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's third consecutive appearance at the Olympics. The National Olympic Committee of the Republic of Uzbekistan sent a total of 70 athletes to the Games, 52 men and 18 women, to compete in 13 different sports, tying its delegation record with Sydney four years earlier. There was only a single competitor in road cycling, artistic and trampoline gymnastics, and table tennis.
Iran competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. The nation has competed at every Summer Olympic games since its return in 1948, after having made their debut in 1900, with the exception of the 1980 and 1984 Summer Olympics. The National Olympic Committee of the Islamic Republic of Iran sent the nation's second-largest delegation to the Games, one less than it sent to Beijing. A total of 53 athletes, 45 men and 8 women, competed in 14 sports. This was also the youngest delegation in Iran's Olympic history, with half the team under the age of 25, and many of them are expected to reach their peak in time for the 2016 Summer Olympics in Rio de Janeiro. Heavyweight boxer Ali Mazaheri was the nation's flag bearer at the opening ceremony.
Uzbekistan competed at the 2012 Summer Olympics in London, from July 27 to August 12, 2012. This was the nation's fifth consecutive appearance at the Olympics. The National Olympic Committee of the Republic of Uzbekistan sent the nation's smallest delegation to the Games in the post-Soviet era. A total of 54 athletes, 36 men and 18 women, competed in 13 sports. There was only a single competitor in fencing, rhythmic and trampoline gymnastics, shooting and tennis.
Italy competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This nation has competed at every Summer Olympic Games in the modern era, except for the 1904 Summer Olympics in St. Louis. The Italian National Olympic Committee sent the nation's smallest delegation to the Games since the 1988 Summer Olympics in Seoul. A total of 285 athletes, 162 men and 123 women, competed in 22 sports.
Ukraine competed at the 2012 Summer Olympics in London, from July 27 to August 12, 2012. This was the nation's fifth consecutive appearance at the Summer Olympics in the post-Soviet era. The National Olympic Committee of Ukraine sent a total of 238 athletes, split equally between men and women, to compete in 21 sports.
Argentina competed at the 2012 Summer Olympics in London, United Kingdom, from 27 July to 12 August 2012. This was the nation's twenty-third appearance at the Summer Olympic Games, having missed only three editions: the 1904 Summer Olympics in St. Louis, the 1912 Summer Olympics in Stockholm, and the 1980 Summer Olympics in Moscow, because of its support for the United States-led boycott.
Bulgaria competed at the 2012 Summer Olympics in London, United Kingdom from 27 July to 12 August 2012. It was the nation's nineteenth appearance at the Summer Olympics, having missed the Olympics on three occasions, including the 1948 Summer Olympics in London due to the nation's role in World War II and 1984 Summer Olympics in Los Angeles because of the Soviet boycott. Despite this being London's third Olympic Games, this was the first time a Bulgarian team appeared at a London Olympics. The Bulgarian Olympic Committee sent the nation's smallest delegation to the Games, tying the record with Helsinki in 1952, and with Tokyo in 1964. A total of 63 athletes, 36 men and 27 women, competed in 16 sports. Men's volleyball was the only team event in which Bulgaria was represented in these Olympic games. There was only a single competitor in badminton, sprint canoeing, fencing, and judo.
Cuba competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's nineteenth appearance in the Olympics. With baseball's removal from the Olympic program and the absence of the nation's volleyball team for the first time, the Cuban Olympic Committee sent the nation's smallest delegation to the Games since 1964. A total of 111 athletes, 66 men and 45 women, competed in 13 sports. There was only a single competitor in archery and table tennis.
Thailand competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's fifteenth appearance at the Olympics, except the 1980 Summer Olympics in Moscow because of its support for the United States boycott.
Algeria competed at the 2012 Summer Olympics in London, United Kingdom, from 27 July to 12 August 2012. This was the nation's twelfth consecutive appearance at the Summer Olympics, except for the 1976 Summer Olympics in Montreal because of the African boycott.
Ecuador competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's twelfth consecutive appearance at the Olympics. It had first competed at the 1924 Summer Olympics in Paris.
Tunisia competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This was the nation's thirteenth appearance at the Olympics, having missed the 1980 Summer Olympics in Moscow because of its partial support for the United States boycott.
Ireland competed at the 2016 Summer Olympics in Rio de Janeiro, Brazil, from 5 to 21 August 2016. This was the nation's twenty-first appearance at the Summer Olympics, having attended every edition, either in its own right or as part of a Great Britain and Ireland team before 1924, with the exception of the 1936 Summer Olympics in Germany.
The team of the Olympic Federation of Ireland, which competed at the 2020 Summer Olympics in Tokyo, represented athletes from both the Republic of Ireland and those from Northern Ireland who choose it instead of the Great Britain and Northern Ireland team. Originally scheduled to take place from 24 July to 9 August 2020, the Games were postponed to 23 July to 8 August 2021, due to the COVID-19 pandemic. It was the team's twenty-second appearance at the Summer Olympics, having attended every edition since 1924 except the 1936 Summer Olympics in Germany.
Great Britain (1896–1920)
