James J Strang.
After Joseph Smith was killed by an angry mob in Illinois on June 27, 1844, a succession crisis ensued in the Mormon Church over who was the rightful heir to lead the growing religion. Most of the candidates were well known within the sect, and were either close advisers to Smith or high ranking members of the church. These men included famous names such as Brigham Young and Oliver Cowdery, as well as Smith's sons.
As these men were debating over who was the rightful successor to the Prophet, out of the blue comes James J. Strang, a relatively unknown church elder who was working to establish Mormonism in the upper Midwest. He possessed a letter (which later came to be known as the "Letter of Appointment"), purported to be written by Smith a week before his death, the contents of which included that Smith knew he was going to be murdered, and that Strang should head the church once he was.
Despite the fact that it's highly questionable that Smith would anoint Strang as his successor instead of one of his right hand men or sons, contemporary and modern analyses of the letter have basically proven that it was a forgery.
But the fake letter, along with stories he told that angels visited him and told him the church was now under his rule, apparently convinced a large number of Mormons to follow Strang. Coincidentally, during this time Strang also claimed to find a new set of golden plates in Wisconsin, similar to the ones that Smith had "translated" into the Book of Mormon years earlier. Of course, these too were fake, fabricated out of a tea kettle, but nonetheless, it added validity to Strang's claims as successor in the eyes of stupid and gullible Mormons.
Eventually he was told to fuck off after being called on his bullshit by some of the higher ups, and when Mormons are calling you on your bullshit, that automatically anoints you as a historically significant, massive bullshitter. After being expelled from Illinois, he started to make his way north, tailed by a large number of followers who bought his story.
All of this power eventually went to his head, and he started to make claims that he was "king" of his people. He and his sect eventually settled on Beaver Island, a fairly sizable chunk of land off the coast of Lake Michigan. Like a good Mormon, he was married to 5 women and had 14 children. He also was a staunch supporter of practicing baptism for the dead and animal sacrifice.
To cement his self-appointed title of king, a coronation celebration was held on Beaver Island, where Strang was presented with a wool robe, a tin crown, a breastplate, and a wooden sword. He wore these in public regularly.
Then the problems began. You see, Beaver Island already had a fairly decent population of people before he got there. And they didn't take too kindly to this insane "prophet" coming in and claiming he was king. He stole land and tax revenue, and in general was a total dick to his non-followers. Strang's followers eventually bullied their way into all of the top governmental positions on the island as well, which just further pissed off everyone else.
The non-Mormons ("gentiles") started rebelling, beating up Strang's followers in broad daylight, robbing Mormon's homes, and rioting in the streets. During one of these riots, King Strang fired a canon into a group of protesters. Strang was also making enemies within his sect. He routinely had some of his people rounded up and punished for petty grievances, leading to tension among his followers.
One of these followers eventually left the colony and began going town to town telling stories of Strang's bullshit. Eventually, the government caught wind and King Strang was arrested and taken to Detroit on charges of treason, counterfeiting, and unlawful seizing of government lands. Somehow, he beat all of the charges, and parlayed all of the press he received into winning a seat in the state House of Representatives. I'm not joking.
Eventually, people had had enough, and rumors began swirling on Beaver Island that there were a group of excommunicated followers who were plotting an assassination. Strang laughed these rumors off.
On June 16, 1865, a US Navy vessel landed on Beaver Island. Two assassins stepped off and greeted Strang on the dock. They started firing rounds, hitting him in the head and spine multiple times. For good measure, they pistol whipped him to a bloody pulp. As this was going on, Navy officers and sailors stood on the deck of the ship and watched, doing nothing to help the dying King. The two assassins were "arrested", given a mock trial, fined $1.25 each, and let go.
Somehow, Strang survived, but he was in rough shape. As he lay on his death bed paralyzed from the bullets in his spine, citizens of neighboring Mackinac Island saw an opening. They rushed onto Beaver Island, forcibly expelling every Mormon onto shitty, rickety ships, and robbed them of all possessions for good measure.
Strang eventually died, and most of his followers joined other Mormon sects. Believe it or not, Strang's church still exists today in Wisconsin, composed of 6 congregations made up of 300 members.
And that, my friends, is perhaps the lulziest moment in the history of the world's lulziest religion.