American religious enthusiast, leader of a movement called Millerism that sought to revive belief that the bodily arrival (“advent”) of Christ was imminent.

Miller was a farmer, but he also held such offices as deputy sheriff and justice of the peace. In the War of 1812 he served as a captain of the 30th Infantry. After years of Bible study he began to preach in 1831 that the present world would end “about the year 1843.” He based this belief primarily on a passage in the Book of Daniel (8:13–14). He published a pamphlet in 1833 and a book of lectures in 1836, the first of many publications. Principal organs of the Millerite movement were the Signs of the Times (Boston) and the Midnight Cry (New York). Miller estimated that between 50,000 and 100,000 believed in his views. When 1843 passed, some of his associates set Oct. 22, 1844, as the date of the Second Coming. This date brought the movement to a sharp climax. There is no historical foundation for stories that the Millerites engaged in such fanatical excesses as ascending hills, housetops, and trees in ascension robes. The last general conference met at Albany, N.Y., April 1845. Belief in the imminence of the advent was restated, but no date was set and no church organization created.

There are two principal Adventist bodies today—the Advent Christian Church, organized in 1861, and the much larger body of Seventh-day Adventists, organized in 1863—and several small Adventist bodies.