Yugoslavia at the 1964 Summer Olympics

Indonesia competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's twelfth appearance at the Olympics, excluding the 1964 Summer Olympics in Tokyo, and the 1980 Summer Olympics in Moscow because of the United States boycott. Krisna Bayu was originally the flag bearer, however the role was later done by Christian Hadinata because Bayu was suffering from flu at the eve of opening ceremony.

Sierra Leone competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. This was the nation's eighth appearance at the Summer Olympics since its debut in the 1968 Summer Olympics. The Sierra Leone delegation included two track and field athletes; Lamin Tucker and Hawanatu Bangura, both of whom were sprinters that were selected via winning an event in Freetown, as the nation had no athletes that met the "A" or "B" standards in any event. Bangura was selected as flag bearer for the opening ceremony. Neither of the two athletes progressed beyond the heats.

Serbia and Montenegro competed at the 2004 Summer Olympics in Athens, Greece, from 13 to 29 August 2004. Previously known as the Federal Republic of Yugoslavia, this was the nation's third and last joint appearance at the Summer Olympics before Serbia and Montenegro became separated independent states in 2006. The Olympic Committee of Serbia and Montenegro sent a total of 85 athletes to the Games, 78 men and 7 women, to compete in 14 sports. Men's basketball, football, volleyball, and water polo were the only team-based sports in which Serbia and Montenegro had its representation at these Games. There was only a single competitor in road cycling, judo, tennis, and wrestling.

Brunei, as Brunei Darussalam, competed at the 2004 Summer Olympics in Athens, Greece, which took place between 13 and 29 August 2004. The country's participation in Athens marked its fourth appearance at the Summer Olympics since its debut in the 1988 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.

The United States competed at the 1972 Summer Olympics in Munich, West Germany. 400 competitors, 316 men and 84 women, took part in 185 events in 21 sports.

The United States of America (USA) competed at the 1992 Summer Olympics in Barcelona, Spain. 545 competitors, 355 men and 190 women, took part in 248 events in 28 sports. At the closing ceremony, a segment of American culture was performed, as the country hosted the next Olympics in Atlanta.

Egypt competed at the 2000 Summer Olympics in Sydney, Australia. 89 competitors, 74 men and 15 women, took part in 64 events in 20 sports. Egyptian competitors did not win any medal at the Sydney Olympics.

The United States competed at the 1964 Summer Olympics in Tokyo, Japan. 346 competitors, 267 men and 79 women, took part in 159 events in 19 sports.

Great Britain, represented by the British Olympic Association (BOA), competed as the host nation for the 1948 Summer Olympics in London. It was the second time that the United Kingdom had hosted the Summer Olympic Games, equalling the record of France and the United States to that point. British athletes have competed in every Summer Olympic Games. 404 competitors, 335 men and 68 women, took part in 139 events in 21 sports.

Malaysia competed at the 1964 Summer Olympics in Tokyo, Japan. It was the first time that the Federation had competed under that name, as it was previously named Malaya, while North Borneo and Singapore had sent separate teams to the Games. 62 competitors, 58 men and 4 women, took part in 49 events in 10 sports.

Chad sent a delegation of two athletes to compete at the 2008 Summer Olympics in Beijing, China: Moumi Sébergué, who competed in the men's 100 meters, and Hinikissia Albertine Ndikert, who competed in the women's 100 meters and also bore the Chadian flag during ceremonies. The appearance of this delegation marked the tenth appearance of Chad at the Summer Olympics, the first been in 1964 Summer Olympics in Tokyo, Japan, and its seventh appearance since its Olympic hiatus between 1976 and 1980. Both Sébergué and Ndikert ranked seventh in their respective heats and did not advance past the qualification round. As of the end of the 2012 London Olympics, there have been no medalists from Chad.

Djibouti took part in the 2008 Summer Olympics, which were held in Beijing, China from 8 to 24 August 2008. The country's participation at Beijing marked its sixth appearance in the Summer Olympics since its debut in 1984. The Djibouti delegation included two athletes in 2008; Mahamoud Farah, a middle-distance runner, and Fathia Ali Bouraleh, a sprinter. Hussein Ahmed Salah, Djibouti's only Olympic medalist, was selected as the flag bearer for both the opening and closing ceremonies despite not competing in 2008. None of the Djiboutian athletes progressed further than the heat round.

Romania competed at the 2012 Summer Olympics in London from 27 July to 12 August 2012. This nation has competed at the Summer Olympic Games since its official debut in 1924, missing only two editions, including the 1948 Summer Olympics. Despite being London's third Olympic Games, this is the first time the Romanian team has competed in London. The Romanian Olympic and Sports Committee sent a total of 103 athletes to the Games, 54 men and 49 women, to compete in 14 sports.

Chad competed at the 2012 Summer Olympics in London, which was held from 27 July to 12 August 2012. This marked the nation's eleventh appearance at the Summer Olympics since its debut in the 1964 Summer Olympics. The Chadian delegation included track and field athlete Hinikissia Ndikert and judoka Carine Ngarlemdana. Ngarlemdana was the flag bearer for the opening ceremony and Ndikert was the flag bearer for the closing ceremony. Neither of Chad's athletes progressed beyond the first round of their events. Chad was one of only two countries to have a female-only team at the 2012 games.

Sierra Leone competed at the 2012 Summer Olympics in London, from 27 July to 12 August 2012. This marked the nation's tenth appearance at the Summer Olympics since its debut in the 1968 Summer Olympics. The Sierra Leone delegation included two track and field athletes; Ibrahim Turay, a sprinter and Ola Sesay, a long jumper. Sesay and Turay were selected as flag bearers for the opening and closing ceremonies respectively. Neither of the two athletes progressed beyond the first round.

Mauritania competed at the 2012 Summer Olympics in London, which was held from 27 July to 12 August 2012. The country's participation at London marked its eighth appearance in the Summer Olympics since its debut in the 1984 Summer Olympics. The delegation included two track and field athletes, Jidou El Moctar and Aicha Fall, who were selected to the team by wildcard places, as the nation had no athletes that met either the "A" or "B" qualifying standards. Moctar was selected as flag bearer for the opening ceremony while a LOCOG Games Maker carried it for the closing ceremony. Neither of the two athletes progressed beyond the heats.

The United States of America (USA) competed at the 2004 Summer Olympics in Athens, Greece. 533 competitors, 279 men and 254 women, took part in 254 events in 31 sports.

Slovenia competed at the 2020 Summer Olympics in Tokyo. Originally scheduled to take place from 24 July to 9 August 2020, the Games were postponed to 23 July to 8 August 2021, because of the COVID-19 pandemic. This was the nation's eighth consecutive appearance at the Summer Olympics as an independent nation. Slovenian athletes won five medals, including three gold, won by canoeist Benjamin Savšek, road racing cyclist Primož Roglič, and sport climber Janja Garnbret. Three gold medals is an all-time record for Slovenia at the Summer Olympics, having previously won two gold in 2000. The Olympics saw the debut of the men's basketball team who finished fourth in the tournament.

Malaysia competed at the 2020 Summer Olympics in Tokyo. 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. Since the nation's official debut in 1956 under the name Malaya, Malaysian athletes have appeared in every edition of the Summer Olympic Games, except for Moscow 1980 in Moscow because of the United States-led boycott.