Kan? Jigor? (?? ???, 28 October 1860 – 4 May 1938[1]) was a Japanese educator and athlete, the founder of Judo. Judo was the first Japanese martial art to gain widespread international recognition, and the first to become an official Olympic sport. Pedagogical innovations attributed to Kan? include the use of black and white belts, and the introduction of dan ranking to show the relative ranking among members of a martial art style. Well-known mottoes attributed to Kan? include "maximum efficiency with minimum effort" (???? seiryoku zen'y?) and "mutual welfare and benefit" (???? jita ky?ei).

Tomita Tsunejir? (?? ???, February 28, 1865 – January 13, 1937), born Yamada Tsunejir? (?? ???), was the earliest disciple of judo. His name appears in the first line of the enrollment book of the K?d?kan.[1] Tomita, together with Saig? Shir?, became the first in the history of judo to be awarded the rank of Shodan by the founder of judo, Kan? Jigor?, who established the ranking system that is now commonly used in various martial arts around the world.[2] Tomita was known as one of the "Four Kings" of K?d?kan judo for his victorious efforts in competing against jujitsu schools.[3] He was awarded 7th dan upon his death on January 13, 1937.[4]

Keiko Fukuda (?? ??, Fukuda Keiko, April 12, 1913 – February 9, 2013) was a Japanese American martial artist. She was the highest-ranked female judoka in history, holding the rank of 9th dan from the Kodokan (2006), and 10th dan from USA Judo (July 2011) and from the United States Judo Federation (USJF) (September 2011), and was the last surviving student of Kan? Jigor?, founder of judo.[1][2][3][4][5][6][7] She was a renowned pioneer of women's judo, together with her senpai Masako Noritomi (1913-1982) being the first woman promoted to 6th dan (c. 1972). In 2006 the Kodokan promoted Fukuda to 9th dan.[8] She is also the first and, so far, only woman to have been promoted to 10th dan in the art of judo.[9] After completing her formal education in Japan, Fukuda visited the United States of America to teach in the 1950s and 1960s, and eventually settled there. She continued to teach her art in the San Francisco Bay Area until her death in 2013.

Kyuzo Mifune (?? ??, Mifune Ky?z?, April 21, 1883 – January 27, 1965) has been categorized as one of the greatest exponents of the art of judo after the founder,[1] Kan? Jigor?. He is considered by many to be the greatest judo technician ever, after Kan?.[1]

Sumiyuki Kotani (?? ??, Kotani Sumiyuki, 1903 – October 19, 1991) was a Japanese martial artist. He was a member of the 1932 Japanese Olympic wrestling team.[1] He was one of the highest ranked judoka, and was awarded a 10th dan in April 1984 by the Kodokan. He was for a long time the oldest 10th dan, until Ichiro Abe was awarded the rank age of 83 years. Kotani studied at the Tokyo College of Education and studied judo directly under Jigoro Kano. As a young man he was known to take on any challenges. Kotani was very active in promoting judo throughout the world and was the director of the international division at the Kodokan for many years. He was also a professor at Tokai University. He was the Kodokan's top representative and vice president of the All Japan Judo Federation. He died on October 19, 1991.

Minoru Mochizuki (?? ?, Mochizuki Minoru, April 7, 1907 – May 30, 2003) was a Japanese martial artist who founded the dojo Yoseikan. He was a 10th dan in Aikido, 9th dan in jujutsu, 8th dan in iaido, 8th dan in judo, 8th dan in kobudo, 5th dan in kendo, 5th dan in karate, and a 5th dan in jojutsu.[1]

Mochizuki was one of the direct students of judo founder Jigoro Kano, aikido founder Morihei Ueshiba and Gichin Funakoshi, founder of Shotokan Karate.[2]

Believing that the martial arts had become distorted by specialization into separate disciplines or transformed into sports, Mochizuki achievement was to assemble back the major techniques of the Japanese martial tradition into a single structure, as it was once practised. He oversaw the development of the system from his home in Shizuoka, Japan, where his dojo, the Yoseikan, was often visited by martial arts practitioners from all over the world.

Mitsuyo Maeda (?? ??, Maeda Mitsuyo, born November 18, 1878 – November 28, 1941),[1] a Brazilian naturalized as Otávio Maeda (Portuguese pronunciation: [o?tavju m??ed?]),[2] was a Japanese jud?ka (judo expert) and prizefighter in no holds barred competitions, also being one of the first documented mixed martial artists of the modern era for he frequently challenged practitioners of other arts and sports. He was also known as Count Combat or Conde Koma in Spanish and Portuguese, a nickname he picked up in Spain in 1908. Along with Antônio Soshihiro Satake (another naturalized Brazilian), he pioneered judo in Brazil, the United Kingdom, and other countries.[1]

Maeda was fundamental to the development of Brazilian Jiu-Jitsu, including through his teaching of Carlos Gracie and others of the Gracie family.[3] He was also a promoter of Japanese emigration to Brazil. Maeda won more than 2,000 professional fights in his career. His accomplishments led to him being called the "toughest man who ever lived" and being referred to as the father of Brazilian Jiu-jitsu.[4]

Yokoyama Sakujir? (?? ???, 1864 – September 23, 1912), was one of the earliest disciples of Kan? Jigor?.[1] He was part of the K?d?kan Shitenn? or Four Guardians of the Kodokan along with Yoshitsugu Yamashita, Tsunejir? Tomita, and Shir? Saig?.[2]

Shiro Saigo (????, Saig? Shir?, February 4, 1866 – December, 1922) was one of the earliest disciples of Judo. Saigo, together with Tsunejiro Tomita, became first in history of judo to be awarded Shodan by the founder of judo Jigoro Kano, who established the kyu-dan ranking system.[1] He was one of the K?d?kan Shitenn? or Four Guardians of the Kodokan along with Yoshitsugu Yamashita, Sakujiro Yokoyama, and Tsunejiro Tomita.[2]

Yamashita Yoshitsugu (?? ??, February 16, 1865 – October 26, 1935, also known as Yamashita Yoshiaki), was a Japanese judoka. He was the first person to have been awarded 10th degree red belt (j?dan) rank in Kodokan judo, although posthumously. He was also one of the Four Guardians of the Kodokan, and a pioneer of judo in the United States.

Mikinosuke Kawaishi (?? ????, Kawaishi Mikinosuke, born 13 August 1899 – 30 January 1969) was a Japanese master of judo who achieved the rank of 7th Dan. He led the development of judo in France, with Shozo Awazu, and much of Europe and is credited with introducing the colored belt system for differentiating early grades. However, written accounts from the archives of London's Budokwai judo club, founded in 1918, record the use of colored judo belts at the 1926 9th annual Budokwai Display, and a list of ranked colored judokas appears in the Budokwai Committee Minutes of June 1927. Kawaishi visited London and the Budokwai in 1928, and was probably inspired to bring the colored belt system to France.[1] The Fédération Française posthumously awarded him 10th Dan in judo and jujutsu.

Antonius Johannes Geesink (6 April 1934 – 27 August 2010)[1][2] was a Dutch 10th dan judoka. He was the first non-Japanese judoka to win gold at the World Judo Championship, a feat he accomplished in 1961 and 1965. He was also an Olympic Champion, having won gold at the 1964 Summer Olympics in Japan, and won a record 21 European Judo Championships during his career.[3]