Igal
Two men named Igal appear in the lists — one of the twelve scouts sent to spy out Canaan, and one of David's mighty men.
Igal the Spy of Issachar
In the roster of the men sent to scout the land, the representative of Issachar is Igal: "Of the tribe of Issachar, Igal the son of Joseph" (Num 13:7). His name appears once, in this list, with no other narrative attached to him beyond the larger account of the scouting mission.
Igal Son of Nathan, of David's Mighty Men
The Samuel roll of David's thirty includes "Igal the son of Nathan of Zobah, Bani the Gadite" (2 Sam 23:36). The Chronicler's parallel list at the same position reads "Joel the brother of Nathan, Mibhar the son of Hagri" (1 Chr 11:38) — preserving the link to Nathan but giving the name as Joel. The two lists describe the same man under the two different forms of the name.
A third Igal also appears in scripture, in the post-exilic Davidic line. Among the sons of Shemaiah listed under Shecaniah, the Chronicler names "Hattush, and Igal, and Bariah, and Neariah, and Shaphat, six" (1 Chr 3:22). This Igal is a descendant of David several generations after the exile, distinct from both the spy of Issachar and the mighty man of Zobah.