Joscelin III (c. 1139 – after 1190) was the titular count of Edessa, who during his lifetime managed to amass enough land to establish a lordship in the Kingdom of Jerusalem.
The county had been captured in 1144 and its remnants (including the Lordship of Turbessel) conquered or sold years earlier.
Joscelin lived in the Kingdom of Jerusalem and managed to gather enough land around Acre to set up his own lordship.
His sister, Agnes, had been the first wife of King Amalric before he succeeded to the throne, and was the mother of Baldwin IV and Sibylla.
Baldwin IV granted part of them, Chastel Neuf, to Joscelin, and awarded Agnes an income from the usufruct, or produce, of Toron.
Joscelin, as the king's maternal grandmother's brother, had no claim, but rather had strong family interests in keeping him alive.
He, in turn, gave them as the dowry of his elder daughter, Beatrice, whom he betrothed to Guy's younger brother, William of Valence.