First ill say i dont believe this, and i didnt type it. i found it on another forum and copy + pasted. I dont think the world is gona end anytime soon,ijust read these for laughs and felt like sharing it.
Doomsday events may include:
 Natural occurrences
Artist impression of what might have caused the Chicxulub crater.
* A global pandemic.
* A geological event such as massive flood basalt, volcanism, or the eruption of a supervolcano. One such event, the Toba Eruption, occurred in Indonesia about 71,500 years ago. According to the Toba catastrophe theory, the event may have reduced human populations to only a few tens of thousands of individuals. Yellowstone Caldera is another such supervolcano, having undergone 142 or more caldera-forming eruptions in the past 17 million years.
* A gamma ray burst or other devastating blast of cosmic radiation. One especially deadly hypothesized source is a hypernova, produced when a hypergiant star explodes and then collapses, sending vast amounts of radiation sweeping across hundreds or even thousands of lightyears of space. Hypernovas have never been observed; however, a hypernova may have been the cause of the Ordovician-Silurian extinction events. The nearest hypergiant is thought to be Eta Carinae, approximately 8,000 light-years distant.
* An abrupt reorientation of Earth's axis of rotation.
* A drastic increase or decrease in the Sun's energy output.
* An impact event caused by the collision of a large meteoroid, asteroid, or comet with Earth. A common theory postulates that the extinction of the dinosaurs occurred approximately 65 million years ago as a result of the Cretaceous-Tertiary extinction event when a large asteroid struck the earth, producing atmospheric dust which blocked solar energy and caused a significant lowering of temperatures worldwide. Evidence for this theory includes a sedimentary layer of iridium in the geological record and a large crater in the area of Chicxulub, Mexico. The Tunguska event (1908) was on a much smaller scale.
* A sudden change in the physical constants governing the universe, such as that created by a vacuum metastability event.
* A close approach of a black hole to the solar system.
* An exceptionally devastating hypercane.
* A universal Big Rip or Big Crunch.
* Severe climate change, caused by natural earth/sun cycles.
In War of the Worlds, Aliens (specifically Martians) attempt a genocide of the human race.
* The creation of a black hole on or close to Earth.
* Depletion of oil or other important natural resources, assuming that alternatives are not explored.
* Strangelet accident.
* A nuclear, chemical, or biological war.
* A cybernetic revolt.
* A grey goo inundation.
* Alien invasion.
* Severe anthropogenic global warming.
 Supernatural events
* An act of divine retribution or the Last Judgment. Many religions include beliefs pertaining to the end of time.
* The Norsemen believed that the world would end in a tremendous battle of the gods known as Ragnarok.
* In the Christian Bible, the Book of Revelation describes Armageddon, a final battle between the forces of God and the forces of Satan
* In Hindu mythology, it is believed the Lord Vishnu will assume his tenth incarnation called Kalki Avatar to destroy the demon Kali and rescue the pure at heart before the world is destroyed.
* According to Strabo, the druids, priests of the Celts, believed that while the universe itself was indestructible, "both fire and water will at some time or other prevail over them" 
The Doomsday Clock
Risks to civilization, humans and planet Earth
Some threats for humanity come from humanity itself. The scenario that has been explored most is a nuclear war or another weapon with similar possibilities. It is difficult to predict whether it would exterminate humanity, but very certainly could alter civilization, in particular if there was a nuclear winter.
Another category of disasters are unforeseen consequences of technology.
It has been suggested that learning computers that rapidly become superintelligent may take unforeseen actions or that robots would out-compete humanity. Because of its exceptional scheduling and organisational capability and the range of novel technologies it could develop, it is possible that the first Earth superintelligence to emerge could rapidly become very, very powerful. Quite possibly, it would be matchless and unrivalled: conceivably it would be able to bring about almost any possible outcome, and be able to foil virtually any attempt that threatened to prevent it achieving its desires. It could eliminate, wiping out if it chose, any other challenging rival intellects, alternatively it might manipulate or persuade them to change their behaviour towards its own interests, or it may merely obstruct their attempts at interference.
Biotechnology could lead to the creation of a pandemic, Nanotechnology could lead to grey goo in which out-of-control self-replicating robots consume all living matter on Earth while building more of themselves - in both cases, either deliberately or by accident. It has also been suggested that physical scientists might accidentally create a device that could destroy the earth and the solar system. Another kind of accident is the Ice-9 Type Transition, in which our planet including everything on it becomes a strange matter planet in a chain reaction. Some do not view this as a credible scenario.
It has been suggested that runaway global warming might cause the climate on Earth to become like Venus, which would make it uninhabitable. In less extreme scenarios it could cause the end of civilization. According to a UN climate report, the Himalayan glaciers that are the sources of Asia's biggest rivers - Ganges, Indus, Brahmaputra, Yangtze, Mekong, Salween and Yellow - could disappear by 2035 as temperatures rise. Approximately 2.4 billion people live in the drainage basin of the Himalayan rivers. India, China, Pakistan, Bangladesh, Nepal and Myanmar could experience floods followed by droughts in coming decades. In India alone, the Ganges provides water for drinking and farming for more than 500 million people. The west coast of North America, which gets much of its water from glaciers in mountain ranges such as the Rocky Mountains and Sierra Nevada, also would be affected. According to the California Department of Water Resources, if more water supplies are not found by 2020, California residents will face a water shortfall nearly as great as the amount consumed today.
Approximately 40% of the world's agricultural land is seriously degraded. In Africa, if current trends of soil degradation continue, the continent might be able to feed just 25% of its population by 2025, according to UNU's Ghana-based Institute for Natural Resources in Africa.
The unlikely creation of a hypothetical microsingularity or exotic matter in particle acceleration experiments, or some unanticipated experimental accident, resulting in destruction of the planet or a large scale disaster.
There were fears (since dismissed) that the first test of an atomic weapon, the Trinity test might have led to ignition of the atmosphere and global destruction. In 2008, concern arose that the Large Hadron Collider might trigger a disaster when activated, although the consensus in the scientific community is that there is no basis for any conceivable threat from the LHC particle collisions.
World War III (also WWIII, or Third World War) denotes a successor to World War II (1939Ã¢â‚¬â€œ1945) that would be on a global scale, with common speculation that it would likely be nuclear and devastating in nature.
In the wake of World War I, World War II, the commencement of the Cold War and the development, testing and use of nuclear weapons, there was early widespread speculation as to the next global war.
This war was anticipated and planned for by military and civil authorities, and explored in fiction in many countries. Concepts ranged from limited use of atomic weapons, to destruction of the planet.