Joseph Smith, founder of the Latter Day Saint movement, and his brother Hyrum Smith, are killed by a mob at the Carthage, Illinois jail.

Joseph Smith, the founder and leader of the Latter Day Saint movement, and his brother, Hyrum Smith, were shot and killed by a mob in Carthage, Illinois, United States, on June 27, 1844, while awaiting trial in the town jail.

As mayor of the city of Nauvoo, Illinois, Joseph Smith had ordered the destruction of the facilities used to print the Nauvoo Expositor, a newly established newspaper created by a group of non-Mormons and others who had seceded from the church. The newspaper's first (and only) issue was highly critical of Smith and other church leaders, reporting that Smith was practicing polygamy and claiming he intended to set himself up as a theocratic king. In response, a motion to declare the newspaper a public nuisance was passed by the Nauvoo City Council, and Smith consequently ordered its press destroyed.The destruction of the press led to public outrage, and the Smith brothers and other members of the Nauvoo City Council were charged with inciting a riot. Warrants for Smith's arrest were dismissed by Nauvoo courts. Smith declared martial law in Nauvoo and called on the Nauvoo Legion to protect the city. After briefly fleeing Illinois, Smith returned and the brothers then voluntarily traveled to the county seat at Carthage to face the charges. After surrendering to authorities, the brothers were also charged with treason against Illinois for declaring martial law.

The brothers were in the Carthage Jail awaiting trial when an armed mob of about 200 men stormed the building, their faces painted black with wet gunpowder. Hyrum was killed almost immediately when he was shot in the face, shouting as he fell, "I'm a dead man, Joseph!" After emptying the pistol with which he tried to defend himself, Joseph was then shot several times while trying to escape from a second-story window, and fell from the window as he died.

Five men were indicted for the killings but were acquitted at a jury trial. At the time of his death, Smith was also running for president of the United States, making him the first U.S. presidential candidate to be assassinated. His death marked a turning point for the Church of Jesus Christ of Latter Day Saints, and since then, members of the Latter Day Saint movement have generally viewed him and his brother as religious martyrs who were "murdered in cold blood".

Joseph Smith Jr. (December 23, 1805 – June 27, 1844) was an American religious leader and founder of Mormonism and the Latter Day Saint movement. When he was 24, Smith published the Book of Mormon. By the time of his death, 14 years later, he had attracted tens of thousands of followers and founded a religion that continues to the present with millions of global adherents.

Smith was born in Sharon, Vermont. By 1817, he had moved with his family to Western New York, the site of intense religious revivalism during the Second Great Awakening. Smith said he experienced a series of visions, including one in 1820 during which he saw "two personages" (whom he eventually described as God the Father and Jesus Christ), and another in 1823 in which an angel directed him to a buried book of golden plates inscribed with a Judeo-Christian history of an ancient American civilization. In 1830, Smith published what he said was an English translation of these plates called the Book of Mormon. The same year he organized the Church of Christ, calling it a restoration of the early Christian church. Members of the church were later called "Latter Day Saints" or "Mormons", and Smith announced a revelation in 1838 that renamed the church as The Church of Jesus Christ of Latter Day Saints.

In 1831, Smith and his followers moved west, planning to build a communal American Zion. They first gathered in Kirtland, Ohio, and established an outpost in Independence, Missouri, which was intended to be Zion's "center place". During the 1830s, Smith sent out missionaries, published revelations, and supervised construction of the Kirtland Temple. Because of the collapse of the church-sponsored Kirtland Safety Society Anti-Banking Company, violent skirmishes with non-Mormon Missourians, and the Mormon extermination order, Smith and his followers established a new settlement at Nauvoo, Illinois, where he became a spiritual and political leader. In 1844, when the Nauvoo Expositor criticized Smith's power and practice of polygamy, Smith and the Nauvoo city council ordered the destruction of their printing press, inflaming anti-Mormon sentiment. Fearing an invasion of Nauvoo, Smith rode to Carthage, Illinois, to stand trial, but he was killed when a mob stormed the jailhouse.

Smith published many revelations and other texts that his followers regard as scripture. His teachings discuss the nature of God, cosmology, family structures, political organization, and religious collectivism. His followers regard him as a prophet comparable to Moses and Elijah. Several religious denominations identify as the continuation of the church that he organized, including The Church of Jesus Christ of Latter-day Saints and the Community of Christ.