Being proved wrong, time and again, never deterred them. The cheekiest simply rescheduled, ignoring the chaos they often caused.
Consider what happened in St Gallen, Switzerland, in 1526. Anabaptists ran through the streets, announcing that the Last Day would arrive in a week.
People stopped work, they got themselves baptised, they started singing and praying. They all felt a bit silly eight days later.
A Spanish monk, Beatus of Liebana, caused a riot when he declared, on the eve of Easter in ad 793, that the world would end that night. Seven years later, he re-announced the dire event, again giving no one any notice.
The master of rescheduling was Joachim of Flores, a 12th-century Italian mystic. It would happen in 1260, he said. When it didn't, his followers plumped for 1290, later postponing to 1335 and then to 1378.
French astrologer Pierre Turrel obviously learned to hedge his bets. When he pronounced doom, he said it would be in 1537, 1544, 1801 or 1814.
Significant dates pose problems for eschatologists, as these prophets of doom are known. Several, including one who based his calculations on the dimensions of the Ark of the Covenant, plumped for ad 500. Then the year 1000 got them excited.
Christian groups predicted the return of Jesus, heralding the Last Judgment. But, oops, they forgot to include the length of Jesus's life in their sums. Humanity had until 1033.
Other people worked round their blunder. Sabbatai Zevi, a Turkish rabbi, said the Messiah would arrive in 1648. When he didn't, Zevi simply announced that he was He. Similarly, Jehovah's Witnesses declared that Jesus would return to start the final ball rolling in 1914. When there was no obvious sign of him, they said he had come back invisible.
And, finally, there have been at least 24 predictions that the world will end between 2006 and 2010. You have been warned.