Nikola Tesla (1856–1943) was a Serbian-American engineer and inventor whose greatest accomplishments were paving the way for practical widespread distribution of electricity by way of the development of alternating current, the Tesla coil (although they were really discovered by Michael Faraday and demonstrated by Callan 20 years before Tesla was born), and having a hand in the creation of radio alongside rivals Guglielmo Marconi and Reginald Fessenden. Though he originally worked for Thomas Edison, they had a falling-out over alternating current and Tesla left to work for Edison's competition.
Tesla was among the most prolific and noted scientists of his time, but made some very poor financial and legal decisions, allowing others such as Edison and George Westinghouse to register patents for his inventions, and he died in relative poverty. The SI unit measure for magnetic field strength is named after him despite the fact that he had no role in the development of electrodynamics, or physics in general. Tesla was also the object of a kind of New Age cult after his death in 1943. Tesla, like Democritus, was convinced that atom is the smallest indivisible unit of matter, and a believer in ether despite the Michelson-Morley experiment.
Cranks had been already attributing either divine or extraterrestrial features to Tesla during his lifetime; he writes in his autobiography jokingly that people can freely call him a monster from planet Venus.
 Tesla's appeal to cranks
While Tesla's major accomplishments went a long way towards creating the world as we know it, he was also something of a mad scientist, dealing in numerous bizarre theoretical (and often unworkable) ideas, including a wireless power transmission system and, most notoriously, a "death ray." Like other pioneering scientists of his era, including Thomas Edison and William Crooke, Tesla was fascinated by the paranormal, the "spirit world" and the possibility of extraterrestrial life. He is also reported to have had various eccentricities and phobias, and it seems rather likely that he suffered from obsessive compulsive disorder.
Tesla's poorly-thought-out later ideas are much beloved of would-be engineers with little formal scientific training, and as a result Tesla's name is sometimes used as a handwave by unscrupulous or naive inventors misrepresenting their inventions.
Tesla is also a favourite figure of conspiracy theorists, and there are numerous theories revolving around him, most of which claim that his death was suspicious and followed some great breakthrough discovery or invention by him which has been kept secret ever since. In some variants, this is the "death ray" he was working on; in others, some form of paranormal or extraterrestrial communication. "The Tesla Conspiracy" site claims that he had discovered the means of drawing electricity directly from the atmosphere, but that this has been hushed up by the interests of unscrupulous oil and energy companies. Further fuel was added to the conspiracists' fire when the US government took control of Tesla's papers after he died.
Another general trope is the notion that Tesla has never received the credit due to him, with his name somehow being suppressed by "the scientific establishment." While it's true that Edison was a bit of a douchebag toward him, and even the patent office now admits that it was Tesla, and not Marconi, who invented the radio, the conspiracy claims go far beyond this. Quite how this tallies with mention of him in every physics textbook is not clear, never mind SI unit of magnetism being named the "tesla" in his honour, as well as a car company also being named after him.
 See also
- See the Wikipedia article on Nikola Tesla.
- Tesla's autobiography; if any source conflict happens, consult this.
- Tesla Memorial Society of New York
- Video of a Tesla coil in action
- Drunk History: Nicola Tesla
- Video of "Edison's Medicine", performed by the American hard rock band Tesla
- Tesla Motors
- Galileo Ferraris
- ↑ A misnomer, since the closest invention is a device firing heavy metal particles at high speed.
- ↑ The Tesla Conspiracy
- ↑ Those who claim to have replicated a Tesla "free energy receiver" have typically re-invented the radio antenna. A radio antenna does draw power "out of the air",i.e. from the earth's magnetic sphere, but that power is measured in milliwatts.