Numbers 31:8

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.

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 (Joshua 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 (Numbers 25:15).

Balaam also ... they slew with the sword. This unprincipled man, on his dismissal from Balak, set out for his home in Mesopotamia (Numbers 24:25); but, either diverging from his way to tamper with the Midianites, he remained among them, without proceeding further, to incite them against Israel, and to watch the effects of his wicked counsel; or, learning in his own country that the Israelites had fallen into the snare which he had laid, and which he doubted not would lead to their ruin, he had, under the impulse of insatiable greed, returned to demand his reward from the Midianites. He was an object of merited vengeance. In the immense slaughter of the Midianitish people; in the capture of their women, children, and property; and in the destruction of all their places of refuge, the severity of a righteous God fell heavily on that base and corrupt race. But, more than all others, Balaam deserved and got the just reward of his deeds, for 'teaching Balak to cast a stumbling-block before the children of Israel' (Revelation 2:14). His conduct had been atrociously sinful, considering the knowledge he possessed, and the revelations he had received of the will of God. For anyone in his circumstances to attempt defeating the prophecies he had himself been the organ of uttering, and plotting to deprive the chosen people of the divine favour and protection, was an act of desperate wickedness, which no language can adequately characterize.