I kill ... I wound ... I will make mine arrows drunk with blood, and my sword shall devour flesh. Deuteronomy 32:39-42
The first book of the Bible has two of God's most famous killings: Noah's Flood and Sodom and Gomorrah. These stories are familiar to nearly everyone, and because they are so familiar they tend to be ignored -- which is a shame, since they reveal so much about the nature of the biblical God.
In the flood, God set an example for Christian parents everywhere. Don't bother teaching your children to behave well; if they misbehave, drown them all.
And in the story of Sodom we learn what it means to be "just and righteous" in the eyes of the Lord. It means to be like Lot, who was the only person in Somdom that God considered worth saving. (Lot offered his virgin daughters to a vicious mob of angel rapers and then got drunk and impregnated them.)
The other Genesis killings have important morals also. Don't look back; don't be wicked in the sight of the Lord; and, for God's sake, don't spill your seed on the ground. And if someone has sex with your sister, kill every male in town after cutting off their foreskins and then enslave their wives and children.
Here's a list of the killings in Genesis:
