Most of the examples of God executing his judgment occur in the Old Testament. This is hardly surprising, given its regular references to blood being shed either by animals (through sacrificial offering of animals) or by humans. Below is a list of individuals (sometimes two at one time) whom God kills due to their sins.
Lot's wife was executed by being immediately turned into a pillar of salt when she disobeyed the command to not view the destruction of Sodom and Gomorrah (Genesis 19:17, 26). She is the first person in the Bible named as receiving the death penalty from God.
Er, the firstborn child of the patriarch Judah, was put to death by the Eternal for his unspecified wickedness (Genesis 38:7). Onan, the second son of Judah, was executed for refusing to fulfill his duty to produce children with his dead brother's widow (Genesis 38:8 - 9).
The Lord commanded the Israelites to stone to death an unnamed man found breaking the Sabbath (Numbers 15:32 - 36).
Abihu and Nadab, the sons of Aaron the High Priest, were specially called to serve in the tabernacle in the wilderness (Exodus 28:1). One day they offered before the altar "strange fire" (KJV translation) before God and were immediately executed for their foolishness (Leviticus 10:1 - 2). Biblical commentaries vary regarding their interpretation of what is meant by "strange fire," the offering of which brought about the swift deaths of these two priests.
Phinehas and Hophni, sons of Eli the High Priest, served as priests at the tabernacle in Shiloh. They took advantage of their authority by coercing those who came to offer an animal sacrifice to give them whatever part of the beast they demanded (1Samuel 2:12 - 17). They also had illicit sex with some of the women who came to worship (1Samuel 2:22).
God declared, through an unnamed prophet, that he would have the two men executed on the same day because of their many sins (1Samuel 2:25, 34). This prophecy was fulfilled when the Philistines not only killed them during a battle but also took from under their care the Ark of the Covenant (1Samuel 4:1 - 11).
Uzzah, a Levite who was helping escort the Ark of the Covenant for King David, was killed instantly when he rashly tried to steady it as it traveled toward Jerusalem (2Samuel 6:7). Hananiah, a false prophet who led the people to believe lies, is executed within a year after he is told by the prophet Jeremiah he will be punished for his sins (Jeremiah 28:12 - 17).
Anyone can receive death
Because Saul, Israel's first king, disobeyed God, he was allowed to lose a fierce battle with the Philistines so that he would lose his life (1Chronicles 10, especially verses 13 - 14).
Nabal was a wealthy but harsh man. He refused, when asked, to provide desperately needed supplies for David (the future king of Israel) and his men. God, ten days after he refused his help, executed him for his wicked behavior (1Samuel 25).
Jeroboam, the first king of the Northern Ten Tribes of Israel, was struck down because of his many sins, chief of which were leading the people away from the true God (2Chronicles 13:20). King Jehoram (also called Joram), the fifth ruler of the Kingdom of Judah, is allowed to contract a fatal bowel disease due to his disobedience (2Chronicles 21:18 - 19).
New Testament Examples
Ananias and his wife Sapphira were New Testament believers. After selling some land, they decided to give the church part of the proceeds but tell everyone that they were donating the entire amount of the sale. The apostle Peter, however, saw through their mutually agreed ruse. After confronting each one separately regarding their lie and selfish attitudes, they are executed through the power of the Holy Spirit (Acts 5:1 - 10).
The angel of the Lord is sent to kill Herod Agrippa, a man who murdered the apostle James and tried to kill Peter, for elevating himself like a god (Acts 12:23). All these, and no doubt countless others we are not aware of, were personally executed by God for their sins!