Who was Jair?
(a) Jair was a son, i.e. descendant of Manasseh (Nu 32:41; Dt 3:14; Josh 13:30; 1 Ki 4:13:1 Ch 2:22 f). According to 1 Ch 2:21 f he was the son of ScRub, son of Hezron, a descendant of Judah, who married the daughter of Machir, son of Manasseh. He was thus descended both from Judah and Manasseh.
At the time of the conquest he distinguished himself by taking the tent-villages. The accounts of his exploit are difficult to harmonize (see ICC on above passages). Some would identify him with the Jair of Jdg 10:3, holding that Manasseh's settlement in Northern Gilead and Bashan took place, not before Israel's passage of the Jordan, but after the settlement of the tribe on the West.
(b) One of the judges. He is said to have had 30 sons, who rode on 30 ass colts, and who had as many cities, known as Havvoth-jair (Jdg 10:3,4). One tradition identifies (a) and (b). Others reconcile the two narratives by interpreting the word "son" in a non-literal sense.
(c) The father of Mordecai (Est 2:5). In the Apocrypha (Additions to Esther 11:2) his name is given as "Jairus" (Grk: Iaeiros).
(2) Jair (Qere: Heb: ya`ir, "he arouses"; Kethibh: Heb: ya`ur; a different name from (1) above): The father of Elhanan, the giant-slayer (1 Ch 20:5). In the parallel passage (2 Sam 21:19) his name is given as "Jaare-oregim," but the text should be corrected to Jair, "oregim" ('oreghim) having crept in from the line below through a copyist's error.
IBSE, "Isaac" (in the public domain) with minor edits.