Sejong of Joseon (May 15, 1397 - April 8, 1450), personal name Yi Do (Korean: 이도; Hanja: 李祹), popularly known as Sejong the Great (Korean: 세종대왕; Hanja: 世宗大王), was the fourth ruler of Korea's Joseon dynasty. He was born as the third son of King Taejong and Queen Wongyeong, and was initially titled Grand Prince Chungnyeong (Korean: 충녕대군; Hanja: 忠寧大君). After his eldest brother, Crown Prince Yi Je, was deposed in 1418, he was designated as heir. Today, King Sejong is regarded as one of Korea's greatest leaders and the most important historical figures in Korea.

Despite ascending to the throne following his father's voluntary abdication in 1418, Sejong was merely a figurehead, with Taejong maintaining real power and governing the country until his death in 1422. Sejong reigned as the sole monarch for the next 28 years, though he became increasingly ill after 1439, and beginning in 1442, his eldest son, Crown Prince Yi Hyang (the future King Munjong), acted as regent.

Sejong strengthened Korean Confucian and Neo-Confucian policies and enacted significant legal changes (공법, 貢法). He personally created and promulgated the Korean alphabet (now known as hangul), encouraged scientific and technological advancements, and introduced economic stimulus measures. He sent military campaigns to the north and established the Samin Jeongchaek ("Peasants Relocation Policy"; 사민정책, 徙民政策) to attract new settlers. During the Ōei Invasion, he assisted in the subjugation of Japanese pirates to the south.

Birthdate: May 15, 1397
Birthplace: Seoul, South Korea
Died: April 8, 1450

Gojong of Korea (July 25, 1852 - January 21, 1919), reigned as the twenty-sixth and final king of Korea's five-century Joseon Dynasty from 1863 to 1907. He reigned in the years preceding the monarchy's demise and Korea's entry into the modern world. Toward the end of his reign, he declared Korea an empire, making him the first emperor of the Korean Empire. The empire was dissolved with Japan's annexation of Korea in 1910, and it was never reestablished.

After taking over the country from his father Daewongun in 1873, Gojong, one of the most important historical figures in Korea allowed most of Daewongun's reforms to stand, most notably the dissolution of the sowons, private academies run throughout the country by yangbans that had become breeding grounds for political factions and enjoyed unbalanced tax-free status. During his reign, Daewongun restored Deoksugung palace, which had been the seat of royal power in Korea for centuries. Unlike Daewongun, King Gojong and Queen Min began to open the country's doors to foreign presence. For the most part, Gojong's intention in forging his alliance with Japan, symbolized by the Treaty of Ganghwa in 1876, was to liberate Korea from China's long-standing hegemony. He went one step further in 1882, establishing a foreign office and welcoming Prussian statesman Paul George Mollendorff as an official advisor to the crown.

At the urging of progressive elements, Gojong of Korea authorized the publication of the nation's first newspaper, the Hansung Sunbo, in 1883, and established a postal system modeled after those in Japan and China the following year. He declared Korea an Empire in 1897, elevating the country to the same level as Japan and China. Later, in 1898, on the advice of the Independence Club, he issued a proclamation establishing a senate and establishing the country as a constitutional monarchy. However, under pressure from current ranking officials who feared losing their influence, he was forced to back down, and the elections were postponed, and eventually canceled entirely. He continued to form alliances, almost all of which were detrimental to Korea, in order to keep the country from being sliced into pieces by the Japanese, Russians, Chinese, and other powers interested in the small peninsular nation and its advantageous location linking Russia and Asia. In the end, his efforts resulted in the country falling under Japanese control in the early twentieth century, where it remained until the end of World War II.

Birthdate: July 25, 1852
Birthplace: Unhyeongung, Seoul, South Korea
Died: January 21, 1919

Yeongjo of Joseon (31 October 1694 - 22 April 1776), personal name Yi Geum (Korean: 연잉군, Hanja: 延礽君), was the twenty-first monarch of Korea's Joseon dynasty. He was King Sukjong's second son by his concubine Royal Noble Consort Suk of the Haeju Choe clan. Prior to assuming power, he was known as Prince Yeoning (Korean:, Hanja:). Because of his biological mother's low-born origins, his life was marked by political infighting and resentment.

Yeoning became Crown Prince in 1720, a few months after his older half-brother, Yi Yun (posthumously known as King Gyeongjong), was crowned as the 20th King. This sparked a heated debate among political factions. Nonetheless, four years later, upon Gyeongjong's death, he ascended to the throne.

Yeongjo's reign lasted nearly 52 years and was marked by his perseverance in reforming the taxation system and minimizing and reconciling factional fighting under his Tangpyeong policy ("Magnificent Harmony"; 蕩平, 탕평). In 1762, his reign was also marked by the highly publicized execution of his only son, Crown Prince Sado. Despite this controversy, Yeongjo's reign has earned a positive reputation in Korean history as a result of his sincere efforts to rule in accordance with Confucian ethics. Therefore, he is regarded as one of the most important historical figures in Korea.

Birthdate: October 31, 1694
Birthplace: Gyeonghuigung, Seoul, South Korea
Died: April 22, 1776

Heungseon Daewongun (흥선대원군, 興宣大院君, 21 December 1820 - 22 February 1898; lit. 'Grand Internal Prince Heungseon'), also known as the Daewongun (대원군, 大院君), Guktaegong (국태공, 國太公, "The Great Archduke") or formally Internal King Heungseon Heonui (흥선헌의대원왕, 興宣獻懿大院王) and also known to contemporary western diplomats as Prince Gung, was the title of Yi Ha-eung, the regent of Joseon during the minority of Emperor Gojong in the 1860s and until his death a key political figure of late Joseon Korea.

Daewongun literally translates as "prince of the great court," a title traditionally bestowed on the reigning monarch's father when the monarch does not reign himself (usually because his son had been adopted as heir of a relative who did reign). While there were three other Daewonguns during the Joseon dynasty, no one was so dominant as Yi Ha-eung in the Joseon dynasty's history that the term Daewongun is usually reserved for him.

Grand Internal Prince Heungseon had to deal with the difficult problems of a new world historical trend while also rebuilding the impoverished nation. The Daewongun is remembered for his "vigorous enforcement of the seclusion policy, persecution of Christians, and the killing or driving off of foreigners who landed on Korean soil" during his regency. The Daewongun died in 1898, just over a year after the Korean Empire was established.

Birthdate: December 21, 1820
Birthplace: Seoul, South Korea
Died: February 22, 1898

Admiral Yi Sun-sin (April 28, 1545 - December 16, 1598) was a Korean admiral and military general known for his victories over the Japanese navy during the Joseon Dynasty's Imjin War. Admiral Yi fought in at least 23 recorded naval engagements, all of which were against the Japanese. He was outnumbered and lacked supplies in the majority of these battles. Despite this, he won battle after battle. His most famous victory was at the Battle of Myeongnyang, where, despite being outnumbered 333 (133 warships, at least 200 logistical support ships) to 13, he managed to disable or destroy 31 Japanese warships while losing only one of his own. Yi died of a gunshot wound at the Battle of Noryang on December 16, 1598, the final battle of the Imjin War.

Yi Sun-sin is widely regarded as one of history's greatest naval commanders, with commentators praising his strategic vision, intelligence, innovations, and personality. In Korea, Yi is regarded as a national hero, with numerous landmarks, awards, and towns named after him, as well as numerous films and documentaries based on his exploits. He is among the most important historical figures in Korea.

Some consider Yi to be a role model for both Koreans and Japanese. Some military historians, such as Joseph Cummins and George Alexander Ballard, rank Yi alongside Admiral Horatio Nelson as one of history's greatest naval commanders.

Birthdate: April 28, 1545
Birthplace: Inhyeon-dong, Jung-gu District, Seoul, South Korea
Died: December 16, 1598

Shin Saimdang (Hangul: 신사임당, Hanja: 申師任堂; 29 October 1504 - 17 May 1551) was a Joseon period Korean artist, writer, calligraphist, and poet. Her birthplace is Gangneung, Gangwon Province. Her birth home, Ojukheon, which is also the home of her maternal family, has been well preserved to this day. She was the mother of Yi I, a Korean Confucian scholar. Her respectful nickname was Eojin Eomeoni ("Wise Mother"), and she was often held up as a model of Confucian ideals. Shin In-seon was her given name. Saim, Saimdang, Inimdang, and Imsajae were her pen names. She was a contemporary of poet Heo Nansseolheon, and the two women were rivals.

Shin Saimdang is the first South Korean woman to appear on a banknote. In June 2009, the Bank of Korea issued the first 50,000 won note. On February 25, 2009, the design for the 50,000 won was unveiled. On the front was a portrait of Shin Saimdang and her drawings, Mokpo Grapes and Chochungdosubyeong (National Treasure No. 595). On the back, paintings (wolmaedo and pungjugdo) were depicted. In contrast to other bills, the illustrations on the back of this bill were drawn vertically. Shin Saimdang was chosen as the main character of 50,000 won by the Bank of Korea on May 5 because she is "a representative female artist in the middle of the Joseon period" and "a person who has accomplished a remarkable achievement in gifted education by fulfilling her wife role." The selection was made because it is expected to contribute to raising awareness of gender equality in Korean society, as well as the importance of education and family (Other 50,000-winners included Kim Gu, Gwanggaeto the Great, Ahn Chang-ho, Jang Yeong-sil, and Ryu Gwan-sun.)

Feminist critics, on the other hand, have criticized this choice for reinforcing sexist stereotypes about women's roles.

Birthdate: October 29, 1504
Birthplace: Gangneung, South Korea
Died: May 17, 1551

Yi Hwang (January 3, 1502 - January 3, 1571) was the Joseon Dynasty's most important philosopher, writer, and Confucian scholar. He was a Neo-Confucian literati figure who founded the Yeongnam School and the Dosan Seowon, a private Confucian academy. Yi Hwang is also known by his pen name Toegye ("Retreating Creek"). Gyeongho was his courtesy name.

Yi Hwang is regarded as Korea's most important philosopher, and his portrait appears on the (most commonly used) 1000 Won banknote, with an image of his school, Dosan Seaowon, on the reverse. His interpretation of Neo-Confucianism influenced not only Korea, but also Japan, Taiwan, and Vietnam, and is now being studied on the Chinese mainland. Ten Diagrams on Sage Learning, which was originally published in classical Chinese, has already been translated into modern Korean, Japanese, Vietnamese, English, French, German, Russian, and Polish. Unfortunately, during the Japanese invasion of Korea, the Japanese military looted some of his writings.

Toegyero Street in central Seoul is named after him. Yi Hwang was honored with the Taekwondo pattern Toi-Gye. Many Yi Hwang-related institutes and university research departments have been established. The Toegye Studies Institute was founded in Seoul in 1970, the Kyungpook National University Toegye Institute in 1979, and Dankook University's Toegye Institute and Library in 1986.

Birthdate: January 3, 1502
Birthplace: Ongye-ri, Andong, North Gyeongsang Province, South Korea
Died: January 3, 1571

Jang Yeong-sil (Korean: 장영실; Hanja: 蔣英實; 1390 - after 1442) was a Joseon Dynasty mechanical engineer, scientist, and inventor (1392-1897). Despite the fact that Jang was born a peasant, King Sejong allowed him to work at the royal palace. Jang's inventions, such as the Cheugugi (the rain gauge) and the water gauge, highlight the Joseon Dynasty's technological advancements.

Jang's fame earned him admission to the royal court at Hanseong (modern-day Seoul), where selected commoners performed for the king and his advisers. Jang exceeded Sejong's expectations in crafts and engineering, earning Jang a position as a government official in the palace. The gifted scientists hired through Sejong's new program worked at the Hall of Worthies.

Jang's extraordinary achievements earned him Sejong's trust. Some government officials were envious of Jang, especially since he had accomplished so much despite his common ancestry. Furthermore, Korean Confucianism, which was deeply rooted in Joseon society, held scientists and engineers in low regard, similar to craftsmen.

In 1442, Sejong commissioned Jang Yeong-sil to create a gama, a lavishly decorated Korean sedan chair. Jang was held responsible for the gama breaking while Sejong was traveling. Despite Sejong's opposition to the decree, Jang was imprisoned for an extended period of time and expelled from the royal palace. Later events in Jang's life, including his death date, were not documented. It is unlikely, but Jang Yeong-sil died during the reign of Joseon's 7th king, Sejo of Joseon (r. 1455-1468).

Birthdate: 1390
Birthplace: South Korea
Died: after 1442

Heo Jun (허준) was a Korean physician who lived from 1546 to 9 October 1615. During the reign of King Seonjo of the Joseon Dynasty in Korea, he was the court physician of the Yangcheon Heo clan.

At the age of 29, Heo Jun was appointed as a court physician. He wrote a number of medical texts, but Dongui Bogam (lit. "Mirror of Eastern Medicine") is widely regarded as the defining text of traditional Korean medicine. The work spread to East Asian countries such as China, Japan, and Vietnam, where it is still considered a classic of Oriental medicine. Although Heo Jun worked extensively with the royal family, he placed a strong emphasis on making treatment methods accessible and understandable to the general public. Rather than using rare and expensive ingredients to increase the perceived value of treatment, he discovered natural herb remedies that were easily accessible to commoners in Korea and were just as effective. Furthermore, he used simple hangul letters to write the names of the herbs rather than the more difficult hanja (Chinese characters) that most people did not understand.

Even today, Koreans recognize Heo Jun's name and accomplishments. Koreans continue to use Heo Jun's natural remedies found in his Dongui Bogam.

Birthdate: 1546
Birthplace: South Korea
Died: October 9 1615

Jeong Yak-yong, sometimes known as Chong Yagyong, was a Korean agronomist, philosopher, and poet. He lived from 5 August 1762 to 7 April 1836 and was frequently referred to as "Dasan" (pen-names that means "the mountain of tea"). Jeong is best known for his work in synthesizing middle Joseon dynasty Neo-Confucian thought. During this time, he wrote extensively in a variety of fields, including law, political theory, and Korean Confucian classics. He aimed to restore Korean Confucian scholarship to a direct connection with Confucius' original thought. This return to the classics was dubbed "Susa" learning (수사, 洙泗), after the two rivers that ran through Confucius' homeland.

He was one of the finest philosophers of the later Joseon era, published books with enormous influence on philosophy, science, and political theory, held important administrative positions, and was a well-known poet. His philosophical perspective is frequently associated with the Silhak (practical learning) school, and his concerns are best understood as explorations of Neo-Confucian themes. He was a close confidant of King Jeongjo (reigned 1776–1800).

Jeong was born in Gwangju, Gyeonggi Province, and he passed away there. Due to his affiliation with the Southerners (Nam-in) side and the Catholic faith of his older brother, he spent 18 years in exile in Gangjin County, South Jeolla Province, from 1801 to 1818. There is no official documentation to support the assertion made by Korean Catholics that Jeong was baptized under the name John Baptist. He was from the Naju Jeong family.

Birthdate: August 5, 1762

Birthplace: Gwangju, Gyeonggi Province, South Korea

Died: April 7, 1836