The Danites were a fraternal organization founded by Latter Day Saint members in June 1838, in the town of Far West, Caldwell County, Missouri. During their period of organization in Missouri, the Danites operated as a vigilante group and took a central role in the events of the 1838 Mormon War. They remained an important part of Mormon and non-Mormon folklore, polemics, and propaganda for the remainder of the 19th century, waning in ideological prominence after Utah gained statehood. Notwithstanding public excommunications of Danite leaders by the Church and both public and private statements from Joseph Smith referring to the band as being both evil in nature and a "secret combination" (a term used in the Book of Mormon to signify corruption within a group of people such as gangs, organized crime, and politics, as well as used in general parlance to signify unlawful conspiracy), the nature and scope of the organization and the degree to which it was officially connected to the Church of Christ (Latter Day Saints) are not agreed between historians. Early in the group's existence, Joseph Smith appeared to endorse its actions, but later turned against it as violence increased and the actions of the Danites inspired a hysteria in Missouri that eventually led to the Extermination Order. According to an essay on the website of the Church of Jesus Christ of Latter-day Saints (LDS Church), "Historians generally concur that Joseph Smith approved of the Danites but that he probably was not briefed on all their plans and likely did not sanction the full range of their activities."

In 1834, during the march of Zion's Camp, a military expedition from Kirtland, Ohio, to Clay County, Missouri, Joseph Smith organized the first Mormon militia known as the "Armies of Israel,", which pre-dated the Nauvoo Legion by eight years, to protect his community. Some historians have alleged this earlier militia to be the original formation of the Danite band. After the 1838 Missouri Mormon War, the term "Danite" was often connected with Latter Day Saint peacekeeping, including the Nauvoo, Illinois police, the bodyguards of Joseph Smith, and the "whistling and whittling brigades". Although some members of these later groups had been Danites in the Missouri period, leadership of the 1838 secret society, which came to be known as "Destroying Angels" in particular under group founder Sampson Avard, was not associated with leadership of the peace-keeping militias commonly referred to by the same name.

The Danites organized in the milieu of mutual hostility and conflict between the Mormon settlers and the more established Missourians, with numerous acts of violence perpetrated on both sides. They were active as a formal organization in Missouri in 1838. They began as a group of zealots determined to drive out internal dissention among the Mormons—dissenters which included former high ranking Mormons including the Three Witnesses—but progressed to becoming involved in militia and paramilitary conflicts with U.S. forces and both civilians and law enforcement of Missouri.

The Latter Day Saint movement had experienced periods of conflict and violence with neighboring communities. Prior to this period, Joseph Smith had promoted a non-violent policy, but this era of pacifism was coming to an end. In August 1833, Smith recorded a revelation that stated:

And now verily I say unto you, concerning the laws of the land, it is my will that my people should observe all things whatsoever I command them. And that law of the land which is constitutional, supporting that principle of freedom in maintaining rights and privileges, belongs to all mankind, and is justifiable before me. Therefore, I, the Lord, justify you and your brethren of my church, in befriending that law which is the constitutional law of the land; And to the law of man, whatsoever is more or less than this, cometh of evil.

This revelation encouraged church members "to bear it patiently and revile not" when "men will smite you, or your families" yet also justified self-defense: If, after being endangered three times, "he has sought thy life and thy life is endangered by him, thine enemy is in thy hands and thou art justified."

Prior to 1838, the Latter Day Saint movement had two centers—one in Kirtland, Ohio and the other in northwestern Missouri. The headquarters and First Presidency of the church were in Kirtland, while the Missouri church was led by a Stake Presidency made up of David Whitmer, W. W. Phelps, and John Whitmer. In 1836, John Whitmer and Phelps founded the town of Far West, Missouri, which became the headquarters of the church in Missouri. Throughout 1837, the church in Kirtland was experiencing internal conflicts over the failure of the church's bank. Ultimately, Joseph Smith and Sidney Rigdon of the First Presidency lost control of the headquarters, including the Kirtland Temple, to dissenters led by Warren Parish. Smith and his followers relocated to Far West, Missouri during the early part of 1838, beginning a period where Smith and other church leaders began to take the view that the church was fighting for its life.

In spring 1838, events came to a boiling point as the number of Mormons swelled in Missouri and Ohio and rifts within the church itself developed. Sudden heavy Mormon immigration, combined with their tendency to vote in a bloc, and their anti-slavery political and northern cultural views aroused hostility from the native Missourians. These tensions were escalated by the fact that Joseph Smith had been issuing prophecies that Missouri was meant to be the chosen place for Zion and the gathering of the Saints. Joseph Smith encouraged the Saints to be unafraid and referred to a passage in the 18th chapter of Judges about the tribe of Dan, "If the enemy comes, the Danites will be after them, meaning the brethren in self-defense." One of those who heard Joseph speak of the Danites was Sampson Avard. Sampson Avard secretly organized some of the brethren into companies for mutual defense and protection. He said he had the sanction of the First Presidency. He also taught those who would follow him that they should lead their companies against the gentiles, to rob and plunder them, and waste them away. With the loot, the kingdom of God would be built. The majority of Avard's followers left him in disgust, and soon Avard was excommunicated.