Kokushi was a shigo (a posthumous name) given to monks by the Emperor and used to express the emperor's respect to the monks.
Other shigos given to monks were the Daishi-go title and the Zenji-go title.
In China, the first case of Kokushi was Hojo (法常) who lived in Northern Qi according to the volume "Kokushi" in "The Essential History of Great-Song Monks" written by Sannei (賛寧) who was the first monk in the Northern Song era. Between the Chen (Nancho) and Sui Dynasties, Chigi (智ギ) was titled as Kokushi. During the Dang Dynasty, Shenxiu who was the sixth head of the Hokushu school of the Zen sect had the Kokushi title. During the reign of Emperor Xianzong during the Tang Dynasty, Chigen (知玄) was given the title of Kokushi as Gotatsu kokushi.
In Japan during the Nara period, each province had a kokushi to control the Buddhist administration in each province.
Persons given kokushi-go in China
Kozo kokushi (康蔵国師) : Hozo (法蔵) (643 - 712), created Avataṃsaka Sutra.
Taisho kokushi (大証国師) : Nan-yang Hui-chung (南陽慧忠) (date of birth unknown - 775) was a Zen monk. He was a disciple of Huineng. He was a master of Emperor Daizong (Tang Dynasty).
Seiryo kokushi (清涼国師): Chokan (澄観) (738 - 839) tried to unify the idea of Avataṃsaka Sutra, Zen and Tendai. He was a master of Guifeng Zongmi. He was a master of Emperor Daizong, Emperor Dezong, Emperor Shunzong, Emperor Xianzong, Emperor Muzong, Emperor Jingzong and Emperor Wenzong during the Tang Dynasty.
Daitatsu kokushi (大達国師): Mugyo (無業) (760 - 821) was a Zen monk. He was a disciple of Mazu Daoyi.
Persons given kokushi-go in Korea
Daishowajo kokushi : Wonhyo (617 - 686) was Seol Chong's father, advocated popular Buddhism and fused Buddhist concepts in Silla.
Daikaku kokushi (大覺国師): Giten (義天) (1055 - 1101) was the patriarch of the Tendai Sect and the fourth son between Emperor Munjong (Emperor of Goryeo) and Empress Jinei ogo (仁睿王后). He learned Vinaya (criminal code), Avataṃsaka Sutra and Zen. He founded the Kokusei-ji Temple (国清寺).
Butsunichifusho kokushi (佛日普照国師): Chinul (1158 -1210) was the patriarch of the Jogye Order and founded Jeonghyesa.
Pogak Kuksa: Iryeon (1206 - 1289) was the author of Samguk Yusa (Memorabilia of the Three Kingdoms) and founded the Ingak-ji Temple.
Shingaku kokushi (眞覺国師): Huichen (1178 - 1234) was the successor of Butsunichifusho kokushi (佛日普照国師).
Ento kokushi (圓證国師): Fugu (普愚) (1301 - 1382) was the patriarch of Rinzai Sect and tried to fuse the Buddhism and Confucianism. The founder of Taegosa-ji Temple.
Shoichi kokushi: Enni (Benen, 1202 - 1280), founder of the Tofuku-ji Temple.
Muso kokushi: Muso Soseki (1275 - 1351) was a chief priest of the Nanzen-ji Temple. Founder of the Tenryu-ji Temple. Founder of the Erin-ji Temple. He was also well-known as a landscape gardener. As he was given seven kokushi titles such as Muso, Shogaku, Shinso (心宗), Fusai, Gennyu, Butto and Daien by each emperor, he was called "Nana Choteishi" (Master for seven emperors).
Kozendaito kokushi: Shuhomyocho (1282 - 1337) was the founder of Daitoku-ji Temple. He was certified for enlightenment at the age of 26, and after that he did Kotsujiki practice (mendicant) for 20 years in Kyoto. He was given two kokushi titles such as Seito and Kozendaito by Emperor Godaigo and Emperor Hanazono.
Daimyo kokushi: Mukan Fumon (1212 - 1291) was the founder of Nanzen-ji Temple. The third chief priest of Tofuku-ji Temple. He was also given the zenji-go title "Busshin zenji" by the emperor. He was a disciple of Enni Benen.
Founder of Enkaku-ji Temple. His school was called the Bukko school and Ogukosai was one of his disciples, Muso Soseki was one of his disciples' disciples.
Entsu daio kokushi: Nanpo Shomyo (1235 - 1308) was the master of Shuhomyocho. He studied under Rankei doryu in Kencho-ji Temple. After he studied Zen, he went to China at the age of 25. Later in his life, he lived in Sofuku-ji Temple in Fukuoka. Along with Koho Kennichi, he was called the "great Kanromon Sutra".
Ogukosai bukkoku kokushi: Koho Kennichi (1241 - 1316) was the third son of Emperor Gosaga. Founder of Ungan-ji Temple. He studied under Mugakusogen. Later, he became priest of the Jomyo-ji Temple, Manju-ji Temple, Jochi-ji Temple, Kencho-ji Temple etc. in Kamakura. Along with Nanpo Shomyo, he was called the "great Kanromon Sutra".
Kosai kokushi: Issan Ichinei (1247 - 1317) was the founder of Jiun-ji Temple. After an expedition failed to Japan during Genko (Mongol invasion attempts against Japan), the Yuan Dynasty tried to submit Japan to them peacefully with Buddhism and sent Issan to Japan. He was the third chief priest of Nanzen-ji Temple.
Honyuensei kokushi (本有円成国師): Kanzan Egen (1277 - 1360) was the founder of Myoshin-ji Temple. Daishi (literally, a great teacher, an honorific title for a high priest) of the Rinzai sect. He was also given other kokushi titles such as Busshin, Kakusho, Daiteiseio (大定聖応), Kotokushomyo (光徳勝妙), Jishotenshin (自性天真) and Homuryoko (放無量光) by the emperors. He studied under Shuho Myocho.
Busuiseizoku kokushi (仏慧正続国師): Gakuin Ekatsu (1357 - 1425) was well-known as a poet of Gozan literature (Chinese poetry done by Zen priests in Kyoto Five-temples during Kamakura-Muromachi Period).
Enshohonko kokushi: Suden (1569 - 1633) served for the bakufu (Japanese feudal government headed by a shogun) during the early Edo period and was called "Kokui no saisho" (a priest who has influence in politics).
Tenodaigen kokushi (天応大現国師):Takuan Soho (1573 - 1645) was the master of Iemitsu TOKUGAWA.
Shoju kokushi: Hakuin (1685 - 1768) was the Chuko no So (father of restoration) of Rinzai sect. He wrote many Japanese versions of Koan (story, dialogue, question, or statement in the history and lore of Zen Buddhism). Shuso (the leader of monks practicing asceticism) of the Myoshin-ji Temple.
Dokofusho kokushi: Koun Ejo (1198 - 1280) promoted to diffuse the faith of Soto sect. The second chief priest of Eihei-ji Temple.
Daikofusho kokushi: Ingen Ryuki (1592 - 1673) was the founder of the Obaku sect. Daishi of the Obaku sect.
Ganji kokushi (鑑智国師): Shoku (1177 - 1277) was the founder of the Jodo Sect Nishiyama School. Zennebo. He was also given the kokushi title of Miten kokushi.
Fukokanchi kokushi: Jisho (1544 - 1620) was the twelfth chief priest of the Zojo-ji Temple. Ieyasu TOKUGAWA became a believer of Ganji kokushi.