I kill ... I wound ... I will make mine arrows drunk with blood, and my sword shall devour flesh. Deuteronomy 32:39-42
There are 18 killings in 2 Kings, more than any other book of the Bible. The first few are especially interesting. God burned 102 men to death for asking Elijah to come down from his hill; he killed Ahaziah for asking the wrong god; and he sent two bears to kill 42 boys for making fun of a prophets bald head.
Most of the rest of the killings were done by a man on a mission from God. That man was King Jehu and the mission was to kill "the whole of the house of Ahab," or at least all who "pissed against a wall." The reason was simple: Ahab didn't kill a captured king.
Jehu started off by killing Ahab's son, Jejoram, and Ahab's wife, Jezebel. Then he had 70 more of Ahab's sons killed, with their heads delivered to him in two baskets. Next, he killed Ahab's hometown family, friends, and priests, Ahaziah's family, and the rest of Ahab's family. And in Jehu's final killing, he assembled the believers of Baal and then slaughtered them all.
Although there are too many killings in 2 Kings to mention here, there are a couple that deserve special attention: God sent lions to kill those who didn't fear him enough, and an angel killed 185,000 sleeping soldiers, who "when they arose early in the morning, behold, they were all dead men."
Here's a list of the killings in 2 Kings:
