Emanuel Swedenborg (/ˈswiːdənbɔːrɡ/, Swedish: [ɛˈmɑ̂ːnʉɛl ˈsvêːdɛnˌbɔrj] ^ⓘ; born Emanuel Swedberg; 29 January 1688 – 29 March 1772) was a Swedish polymath; a scientist, engineer, astronomer, anatomist, Christian theologian, philosopher, and mystic. He became best known for his book on the afterlife, Heaven and Hell (1758).

Swedenborg had a prolific career as an inventor and scientist. In 1741, at 53, he entered into a spiritual phase in which he began to experience dreams and visions, notably on Easter Weekend, on 6 April 1744. His experiences culminated in a "spiritual awakening" in which he received a revelation that Jesus Christ had appointed him to write The Heavenly Doctrine to reform Christianity. According to The Heavenly Doctrine, the Lord had opened Swedenborg's spiritual eyes so that from then on, he could freely visit heaven and hell to converse with angels, demons, and other spirits and that the Last Judgment had already occurred in 1757, the year before the 1758 publication of De Nova Hierosolyma et ejus doctrina coelesti (English: Concerning the New Jerusalem and its Heavenly Doctrine).

Over the last 28 years of his life, Swedenborg wrote 18 published theological works—and several more that remained unpublished. He termed himself a "Servant of the Lord Jesus Christ" in True Christian Religion, which he published himself. Some followers of The Heavenly Doctrine believe that of his theological works, only those that were published by Swedenborg himself are fully divinely inspired. Others have regarded all Swedenborg's theological works as equally inspired, saying for example that the fact that some works were "not written out in a final edited form for publication does not make a single statement less trustworthy than the statements in any of the other works". The New Church, also known as Swedenborgianism, is a Restorationist denomination of Christianity originally founded in 1787 and comprising several historically related Christian churches that revere Swedenborg's writings as revelation.

Swedenborg's father, Jesper Swedberg (1653–1735), descended from a wealthy mining family, bergsfrälse (early noble families in the mining sector), the Stjärna family, of the same patrilineal background as the noble family Stiernhielm, the earliest known patrilineal member being Olof Nilsson Stjärna of Stora Kopparberg. He travelled abroad and studied theology, and on returning home, he was eloquent enough to impress the Swedish king, Charles XI, with his sermons in Stockholm. Through the king's influence, he would later become professor of theology at Uppsala University and Bishop of Skara.

Jesper took an interest in the beliefs of the dissenting Lutheran Pietist movement, which emphasised the virtues of communion with God rather than relying on sheer faith (sola fide). Sola fide is a tenet of the Lutheran Church, and Jesper was charged with being a pietist heretic. While controversial, the beliefs were to have a major impact on his son Emanuel's spirituality. Jesper furthermore held the unconventional belief that angels and spirits were present in everyday life. This also came to have a strong impact on Emanuel.

In 1703–1709, aged 15–21, Emanuel Swedenborg lived in Erik Benzelius the Younger's house. He completed his university course at Uppsala in 1709, and in 1710, he made his grand tour through the Netherlands, France and Germany before reaching London, where he would spend the next four years. It was a flourishing centre of scientific ideas and discoveries. He studied physics, mechanics and philosophy and read and wrote poetry. According to the preface of a book by the Swedish critic Olof Lagercrantz, Swedenborg wrote to his benefactor and brother-in-law Benzelius that he believed he might be destined to be a great scientist.

In 1715, aged 27, Swedenborg returned to Sweden, where he devoted himself to natural science and engineering projects for the next two decades. A first step was his meeting with King Charles XII of Sweden in the city of Lund, in 1716. The Swedish inventor Christopher Polhem, who became a close friend of Swedenborg, was also present. Swedenborg's purpose was to persuade the king to fund an observatory in northern Sweden. However, the warlike king did not consider this project important enough, but did appoint Swedenborg to be assessor-extraordinary on the Swedish Board of Mines (Bergskollegium) in Stockholm.

From 1716 to 1718, aged 30, Swedenborg published a scientific periodical entitled Daedalus Hyperboreus ("The Northern Daedalus"), a record of mechanical and mathematical inventions and discoveries. One notable description was that of a flying machine, the same he had been sketching a few years earlier.