Moses
Numbers 31:8ESV·traditional attribution

They killed the kings of Midian with the rest of their slain, Evi, Rekem, Zur, Hur, and Reba, the five kings of Midian. And they also killed Balaam the son of Beor with the sword.

John Gill Reformed Baptist @doctorgill

And they slew the kings of Midian, beside the rest of them that were slain,.... Besides the males of the common people, they slew their kings, who were petty kings or princes, perhaps under the king of Moab, or had reassumed their titles and government after the death of Sihon the king of the Amorites, who, in his time, were called dukes of Sihon, Jos...

Jamieson-Fausset-Brown Reformed @jfbcommentary

the kings of Midian--so called, because each was possessed of absolute power within his own city or district; called also dukes or princes of Sihon (Jos 13:21), having been probably subject to that Amorite ruler, as it is not uncommon in the East to find a number of governors or pachas tributary to one great king. Zur--father of Cozbi (Num 25:15). Balaam also . . .

Geneva Bible Notes Reformed @genevanotes

And they slew the kings of Midian, beside the rest of them that were slain; [namely], Evi, and Rekem, and Zur, and Hur, and Reba, five kings of Midian: Balaam also the son of Beor they slew with the sword. (c) The false prophet who gave counsel how to cause the Israelites to offend their God.