The Tribe of Reuben (רְאוּבֵן, Standard Hebrew Rəʾuven, Tiberian Hebrew Rəʾûḇēn) is one of the Hebrew tribes, founded by Reuben son of Jacob.

At the Exodus numbered 46,500 male adults, from twenty years old and upwards (Num. 1:20, 21), and at the close of the wilderness wanderings they numbered only 43,730 (26:7). This tribe united with that of Gad in asking permission to settle in the "land of Gilead," "on the other side of Jordan" (32:1-5). The lot assigned to Reuben was the smallest of the lots given to the trans-Jordanic tribes. It extended from the Arnon, in the south along the coast of the Dead Sea to its northern end, where the Jordan flows into it (Josh. 13:15-21, 23). It thus embraced the original kingdom of Sihon. Reuben is "to the eastern tribes what the Tribe of Simeon is to the western. 'Unstable as water,' he vanishes away into a mere Arabian tribe. 'His men are few;' it is all he can do 'to live and not die.' We hear of nothing beyond the multiplication of their cattle in the land of Gilead, their spoils of 'camels fifty thousand, and of asses two thousand' (1 Chr. 5:9, 10, 20, 21). In the great struggles of the nation he never took part. The complaint against him in the song of Deborah is the summary of his whole history. 'By the streams of Reuben,' i.e., by the fresh streams which descend from the eastern hills into the Jordan and the Dead Sea, on whose banks the Bedouin chiefs met then as now to debate, in the 'streams' of Reuben great were the 'desires'", i.e., resolutions which were never carried out, the people idly resting among their flocks as if it were a time of peace (Judg. 5:15, 16). Stanley's Sinai and Palestine.

All the three tribes on the east of Jordan at length fell into complete apostasy, and the time of retribution came. God "stirred up the spirit of Pul, king of Assyria, and the spirit of Tiglath-Pileser III, king of Assyria," to carry them away, the first of the tribes, into captivity (1 Chr. 5:25, 26).