Joscelin of Courtenay (or Joscelin I) (died 1131), Prince of Galilee and Lord of Turbessel (1115–1131) and Count of Edessa (1119–1131), ruled over the County of Edessa during its zenith, from 1118 to 1131. He maintained the large and unstable borders through his martial prowess.
He was the son of Joscelin I, Lord of Courtenay, born in 1034, and wife Isabella (or Elizabeth), daughter of Guy I of Montlhéry. He arrived in the Holy Land during the Crusade of 1101 after the First Crusade, and entered first into the service of his cousin Count Baldwin II of Rethel (in the army of Godfrey of Bouillon), who invested him with the lordship of Turbessel, and later in the army of Stephen of Blois. In 1104 he was captured at the Battle of Harran. By 1113, he had carved out a semi-autonomous state around Turbessel to the west of the Euphrates, where the land was prosperous, while Baldwin II controlled the territory east of the Euphrates around Edessa itself, which was depopulated and continually harassed by the Turks. That year, Baldwin dispossessed him of Turbessel, and Joscelin travelled to Jerusalem, where he was given the title of Prince of Galilee.
In 1118, Baldwin II succeeded Baldwin I as king of Jerusalem. Despite their former hostility, Joscelin fully endorsed Baldwin II, over the candidacy of Baldwin I's brother Eustace III of Boulogne. Joscelin was rewarded with the County of Edessa.
As count, he was taken prisoner along with Galeran, lord of Bira, in 1122 near Saruj by Belek Ghazi. Later he was joined in captivity at Kharput, by Baldwin II, king of Jerusalem, who had been captured in April 1123. They were rescued by fifty Armenian soldiers, who disguised themselves as merchants and infiltrated the fortress where the prisoners were kept. They killed the guards and freed the hostages. However, the castle was soon besieged by a large Turkish force and it was decided that Joscelin should seek assistance. Baldwin stayed in the fortress and after some time it was reclaimed by the Turks.
After returning to Edessa he was able to enlarge the territory of the county, and in 1125 he participated in the Battle of Azaz, a Crusader victory against the atabeg of Mosul, who were led by Il-Burzuki.
In 1131, during the siege of a small castle north-east of Aleppo, a sapper's mine collapsed and Joscelin was gravely injured. Shortly thereafter, he received word that emir Ghazi II Danishmend was marching against the fortress town of Kaysun. When Joscelin's own son, the future Joscelin II, refused to aid the town, he commanded that his own army should decamp and Joscelin was borne on a litter before the army. When Ghazi heard of Joscelin's approach, perhaps mistakenly believing him already dead, he lifted the siege and retreated, and thus the warrior prince won a final battle before dying shortly thereafter on the roadside.
Joscelin married an Armenian noblewoman named Beatrice, daughter of Constantine I of Armenia. Beatrice was the mother of his son
- Joscelin II, Count of Edessa.
In 1122, after Beatrice died (d. 1119), Joscelin married Maria, daughter of Richard of Salerno and sister of Roger, regent of the Principality of Antioch.