Prophecy

Prophecy is speaking for God or for the gods (pro- meaning for), sometimes involving predicting the future (pro- meaning before in time), often using "impending doom" and "fires of destruction" and "destruction of the world" as the culminating theme. Prophecies are usually reserved for important figures like kings and leaders and of course generally predict the downfall of bad rulers and the eventual return of "all that is Good and True" if and only if the "people" follow the right "path".

Prophecy is often a result of the prophet's dreams, altered states, or high levels of in their life. Incidentally, none of these conditions are conducive to logical thinking.

In fiction
Fantastical fiction (including some forms of sci-fi) often features ancient prophecies, frequently involving a "chosen one" who will triumph over evil in some way or restore a balance that was lost a long time ago. Such messianic prophecies are readily believed without question by the people in these stories, and invariably turn out to be correct.

In the real world
In the real world, prophecies tend to be open to interpretation and skepticism. They are also a lot more vague so they can be shoehorned to fit whatever actually happens. Examples include:
 * The ambiguous Delphic oracle, popular during the last millennium BCE. A drugged priestess mumbled and male priests interpreted what she said in ways that could fit a wide range of events.
 * The cryptic ramblings of Nostradamus, whose 'predictions' of future events can only be figured out properly after such events have already happened.

Famous prophecies

 * Daniel and the Wall
 * Nostradamus
 * Joseph Smith, Jr. and the Book of Mormon
 * Book of Revelation
 * David Wilkerson, a Christian evangelist who successfully prophesied that the end of the world would be in 1973 1999 2009 (despite the world apparently continuing, we at RationalWiki maintain that this prophecy was, in fact, correct).
 * Merlin seeing the eventual fall of King Arthur
 * Saint Malachy's predictions about future popes
 * Some guy foreseeing that the Witch-king of Angmar would not be slain by a man. He could have phrased it less obtusely.
 * Wovoka's vision of (for?) the Ghost Dance
 * Ed Dames — on 9 April 2005, on Coast to Coast AM, Dames warned that we've reached the "beginning of the end," and can expect "a very serious series of events that will kill a lot of people" shortly after the Space Shuttle is forced down by a meteor shower. He said the window for the coming catastrophe falls within the next five years, and advised people to live in places with plentiful fresh water and underground protection.
 * Mother Shipton