Coloman the Learned, also the Book-Lover or the Bookish (Hungarian: Könyves Kálmán; Croatian: Koloman; Slovak: Koloman Učený; c. 1070 – 3 February 1116), was King of Hungary from 1095 and King of Croatia from 1097 until his death. Because Coloman and his younger brother Álmos were underage when their father Géza I died, their uncle Ladislaus I ascended the throne in 1077. Ladislaus prepared Coloman—who was "half-blind and humpbacked", according to late medieval Hungarian chronicles—for a church career, and Coloman was eventually appointed bishop of Eger or Várad (Oradea, Romania) in the early 1090s. The dying King Ladislaus preferred Álmos to Coloman when nominating his heir in early 1095. Coloman fled from Hungary but returned around 19 July 1095 when his uncle died. He was crowned in early 1096; the circumstances of his accession to the throne are unknown. He granted the Hungarian Duchy—one-third of the Kingdom of Hungary—to Álmos.

In the year of Coloman's coronation, at least five large groups of crusaders arrived in Hungary on their way to the Holy Land. He annihilated the bands who were entering his kingdom unauthorized or pillaging the countryside, but the main crusader army crossed Hungary without incident. He invaded Croatia in 1097, defeating its last native king Petar Snačić. Consequently, he was crowned king of Croatia in 1102. According to the late 14th-century Pacta conventa (the authenticity of which is not universally accepted by scholars), he was only crowned after having ratified a treaty with the leaders of the Croatian nobility. For centuries thereafter, the Hungarian monarchs were also the kings of Croatia.

Coloman had to face his brother's attempts to dethrone him throughout his life; Álmos devised plots to overthrow him on at least five occasions. In retaliation, he seized his brother's duchy in 1107 or 1108 and had Álmos and Álmos' son Béla blinded in about 1114. Hungarian chronicles, which were compiled in the reigns of kings descending from his mutilated brother and nephew, depict Coloman as a bloodthirsty and unfortunate monarch. On the other hand, he is portrayed as "the most well-versed in the science of letters among all the kings of his day" by the contemporaneous chronicler Gallus Anonymus. Coloman's decrees, which governed many aspects of life—including taxation, trade and relations between his Christian and non-Christian subjects—remained unmodified for more than a century. He was the first Hungarian king to renounce control of the appointment of prelates in his realms.

Coloman was the elder of the two sons of King Géza I who survived infancy. Géza's Byzantine second wife, whose baptismal name is unknown, left Hungary after her husband's death, implying that she was not his children's mother. Consequently, the mother of Coloman and his younger brother, Álmos, must have been Géza's first wife, Sophia, whose family is unknown. According to historians Gyula Kristó and Márta Font, the brothers were born around 1070, because they were mature enough to hold offices in the early 1090s. Coloman's uncommon baptismal name was recorded as Colomanus or Colombanus in medieval documents written in Latin. Kristó writes that he was most probably named after Saint Coloman of Stockerau, a missionary who was martyred in Austria in the early 11th century. Another possibility is that his name is of Turkish origin (meaning "rest"), because his brother bore a Turkish name.

Coloman's father ascended the throne in 1074. Because Coloman and Álmos were minors when he died on 25 April 1077, Géza's brother Ladislaus I succeeded him. The new king decided that Coloman should be prepared for a career in the Church. The king's decision was unusual as Coloman was older than Álmos and elder brothers were rarely ordained priests. The 14th-century Illuminated Chronicle stated that Coloman was "of mean stature, but astute and quick of apprehension", adding that he was "shaggy and hirsute, half-blind and humpbacked, and he walked with a limp and stammered in his speech". If the chronicle preserved genuine tradition of his appearance, his physical deformity may have influenced his uncle's decision. However, modern scholars tend to refute this view, emphasizing that the chronicle was completed in the reigns of kings descending from Álmos.

In preparation for his clerical life, Coloman learnt to read and write and acquired a good knowledge of Latin. His proficiency in canon law was praised in a letter that Pope Urban II addressed to him in 1096. According to Kristó, upon finishing his studies he was ordained priest and in the early 1090s was appointed bishop. Hungarian chronicles completed in the 14th and 15th centuries say that Coloman was bishop of either Eger or Várad. For instance, the Illuminated Chronicle states that he was "bishop of Warad" (or Várad), and Ladislaus I wanted to appoint him "bishop of Agria" (or Eger).

According to the Illuminated Chronicle, both Coloman and Álmos accompanied their uncle on a military campaign against Bohemia in early 1095. Before reaching the border of his kingdom, Ladislaus I "was overcome by a grave infirmity" and decided to appoint Álmos as his heir. Instead of obeying his uncle's decision, Coloman fled to Poland. He returned to Hungary around 29 July 1095 when his uncle died. The exact circumstances of his ascension to the throne are uncertain. The Illuminated Chronicle states Ladislaus had invited him back from Poland. The same source adds that Álmos, "in the true simplicity of his heart honoured his brother, Coloman, and yielded to him the crown of the kingdom", which suggests that he ascended the throne without bloodshed. On the other hand, Coloman was crowned king in early 1096, the delay implying that the two brothers had been fighting for the crown before they reached an agreement. It is also possible, as proposed by Font, that he could only be crowned after Pope Urban II had released him from his clerical vows.

Coloman was crowned in Székesfehérvár by Archbishop Seraphin of Esztergom. According to the Illuminated Chronicle, at the same time he "granted the dukedom with full rights" to Álmos. This report shows that Álmos only acknowledged his brother's rule in exchange for receiving the duchy once held by their father and grandfather, an area that comprised one third of the territory of the kingdom.