Jehu, son of Jehoshaphat and grandson of Nimshi, was a ruthless king of Israel chosen by God to destroy the house of Ahab, his predecessor. Anointed by a servant of Elisha, he conspired against King Joram shooting him through the heart with an arrow. He then had Joram's body thrown into Naboth's vineyard.
He then had Jezebel, Ahab's remaining sons, 40 relatives of Ahaziah, and the followers of Baal killed. After Jehu ended Baal worship in Israel, God promised him that his great-great-grandson would rule Israel.
In spite of his zeal, Jehu went far beyond his appointed task. Having killed the king of Israel, he turned his wrath on Ahaziah, King of Judah. After this, he turned away from God unto the false religion of Israel, worshiping the golden calves.
Jehu was the son of Jehoshaphat, and was sometimes referred to as the son of his grandfather Nimshi. He lived as a soldier in Israel's army, and worked his way up through the ranks and was eventually a commander. He lived during the reign of king Joram.
Jehu is a translation of the Hebrew name יֵהוּא (yay-hoo), which means "the Lord is He." It comes from two Hebrew words: יְהֹוָה (yeh-ho-vaw) and הוּא (hoo). יְהֹוָה is the sacred name of God, which is translated as Yahweh, Jehovah, or the Lord. הוּא means "he, she, or it" — the exact definition depends on the context.