Who was Zebah?
Zebah was one of Midian's two kings (Judg. 8:5-21; Ps. 83:11). Oreb and Zeeb were the prince-generals of Midian, slain by the Ephraimites at the central fords of the Jordan (Judg. 7:25).
Zebah and Zalmunna were their kings slain by Gideon at Karkor, high up on the Hauran, where they had fled by the ford further to the N. and on through Gilead.
Their murder of his brothers (three at least, as not the dual but plural is used) at Tabor was what, in spite of hunger and faintness, especially stimulated Gideon to such keenness in the pursuit.
IBSE, "Isaac" (in the public domain) with minor edits.