William Miller, Mr. "Great Disappointment"
Alleged judgment day: 10/22/1844
You know you caught a bad break in life when the thing you are best known for has "disappointment" in the title. Poor William Miller. For nearly a decade, the preacher was proclaiming to anyone who would listen that the second coming of Jesus would happen on October 22, 1844, which would then lead to the end of the world. Miller created so much noise that his followers ended up believing him.
Well, we don’t need to tell you that this didn’t happen. After the day came and went and there wasn't any massive outbreak of death, Miller had some serious 'splainin to do. He had nothing useful to say, of course, so the people ended up labeling his failed theory as “The Great Disappointment.” Man, how fucked were the 1800s that mass death not happening was seen as a disappointment?