Joscelin II of Edessa (died 1159) was the fourth and last ruling count of Edessa.
The young Joscelin was taken prisoner at the Battle of Azaz in 1125, but was ransomed by Baldwin II, king of Jerusalem. In 1131, his father Joscelin I was injured in battle with the Danishmends, and Edessa passed to Joscelin II. Joscelin II refused to march the small Edessan army out to meet the Danishmends, so Joscelin I, in his last act, forced the Danishmends to retreat, dying soon after.
Joscelin II ruled the weakest and most isolated of the Crusader states. In 1138 he allied with Antioch and Byzantine emperorJohn II Comnenus to attack Zengi, atabeg of Aleppo, although Zengi defeated them. Back in Antioch, sentiment agains the Byzantine Empire, which John was trying to extend into the northern Crusader states, led to a riot, engineered by Joscelin. John was forced to return home.
In 1143 both John II and Fulk of Jerusalem died, leaving Joscelin with no powerful allies to help defend Edessa. In 1144 Zengi invaded and captured Edessa itself. Joscelin fled to Turbessel, where he held the remnants of the county west of the Euphrates. When Zengi died in 1146, Joscelin attempted to recapture Edessa but was defeated by Zengi's son Nur ad-Din. The Second Crusade, called in response to the fall of Edessa, was also unable to defeat the Muslims. Joscelin was taken prisoner in 1150 and died in 1159.
Baldwin II was succeeded in 1131 by his daughter Melisende, who ruled jointly with her husband Fulk, the former Count of Anjou.
To balance this, the king turned from time to time to his uncle, Joscelin III of Edessa, after he was ransomed in 1176: as his maternal kin, the Courtenay family had no claim to the throne.
Indeed, the sheer size of Frederick II's army and his stature before the Islamic world was sufficient to regain Jerusalem, Bethlehem, Nazareth, and a number of surronding castles without a fight: these were recovered by treaty with the Ayyubid Sultan Al-Kamil.