Hari Seldon is a fictional character in Isaac Asimov's Foundation Series. In his capacity as mathematics professor at Streeling University on Trantor, Seldon develops psychohistory, allowing him to predict the future in probabilistic terms. His prediction of the eventual fall of the Galactic Empire is the reason behind his nickname "Raven" Seldon.
In the first five books of the Foundation Series, Hari Seldon made only one in-the-flesh appearance, in the first chapter of the first book (Foundation), although he did appear other times in pre-recorded messages in order to reveal a Seldon Crisis. After writing five books in chronological order, Asimov went back with two books to better describe the initial process. The two prequels—Prelude to Foundation and Forward the Foundation— describe his life in considerable detail. He is also the central character of the Second Foundation Trilogy written after Asimov's death (Foundation's Fear by Gregory Benford, Foundation and Chaos by Greg Bear, and Foundation's Triumph by David Brin), which are set after Asimov's two prequels.
Galactic Empire First Minister and Psycho-Historian Hari Seldon was born in the 10th month of the 11,988th year of the Galactic Era (GE) (-79 Foundation Era (FE)) and died 12,069 GE (1 FE). (In Asimov's saga, the Galactic Era begins when the Galactic Empire is founded at an unknown date roughly 11,000 years in the future: the timeline can be deduced from some hints Asimov dropped in his other science fiction works, including the Robot and Empire series.)
He shows incredible mathematical abilities at a very early age. He also learns martial arts on Helicon that later help him on Trantor, the principal art being Heliconian Twisting (a form seemingly equal parts Jiu Jitsu, Krav Maga, and Submission Wrestling). Helicon is said to be "less notable for its mathematics, and more for its martial arts" (Prelude to Foundation).
Seldon is the subject of a biography by Gaal Dornick. Seldon is Emperor Cleon I's second and last First Minister, the first being Eto Demerzel/R. Daneel Olivaw. He is deposed as First Minister after Cleon I's assassination.
Seldon, Hari— . . . found dead, slumped over desk in his office at Streeling University in 12,069 (1 F.E.). Apparently Seldon had been working up to his last moments on psychohistorical equations; his activated Prime Radiant was discovered clutched in hand. According to Seldon’s instructions, the instrument was shipped by his colleague Gaal Dornick who had recently emigrated to Terminus. Seldon's body was jettisoned into space, also in accordance with instructions he’d left. The official memorial service on Trantor was simple, though attended. It was worth noting that Seldon’s old friend former First Minister Eto Demerzel attended the event. Demerzel had not been seen since his mysterious disappearance immediately following the Joranumite Conspiracy during the reign of Emperor Cleon I. Attempts by the Commission of Public Safety to locate Demerzel in the days following the Seldon memorial proved to be unsuccessful. Wanda Seldon, Hari Seldon’s granddaughter, did not attend the ceremony. It was rumored that she was grief-stricken and had refused all public appearances. To this day, her whereabouts from then on remain unknown. It has been said that Hari Seldon left this life as lived it, for he died with the future he created unfolding all around him.
Using psychohistory, Seldon mathematically determines what he calls The Seldon Plan--a plan to determine the right time and place to set up a new society, one that would replace the collapsing Galactic Empire by sheer force of social pressure, but over only a thousand-year time span, rather than the ten-to-thirty-thousand-year time span that would normally have been required, and thus reduce the human suffering from living in a time of barbarism. The Foundation is placed on Terminus, a planet entirely populated by scientists and their families. The planet was originally occupied to create the Encyclopedia Galactica, a vast compilation of the knowledge of a dying galactic empire.
Prelude to Foundation 
As a 32-year-old assistant professor of mathematics at Helicon University, Seldon visits Trantor from his native Helicon to attend the Decennial Mathematics Convention. He presents a paper which indicates that one could theoretically predict the Galactic Empire's future. At first, Seldon has no idea how this could be done in practice, and he is fairly confident that no one could actually fulfill the possibility. Shortly after his presentation, he becomes a lightning rod for political forces who want to use psychohistory for their own purposes. The rest of the novel tells of his flight, which lasts for approximately a year and which takes him through the complex and variegated world of Trantor. During his flight to escape the various political factions, he discovers how psychohistory can be made a practical science. It is in this novel that he meets his future wife Dors Venabili, future adopted son Raych Seldon, and future partner Yugo Amaryl.
Forward the Foundation 
This novel is actually told as a sequence of short stories, just as was the case with the original trilogy. They take place at intervals a decade or more apart, and tell the story of Hari's life, starting about ten years after Prelude and ending with his death. The stories contrast his increasingly successful professional life with his increasingly unsuccessful personal life.
Seldon becomes involved in politics when Eto Demerzel becomes a target for a smear campaign conducted by Laskin Joranum. He eventually takes Demerzel's place as First Minister, despite his reluctance to divide his attention between government and the development of Psychohistory. His career comes to an end when Cleon I is assassinated by his gardener (a random event Seldon could not have predicted) and the seizure of power by a military junta. Seldon eventually causes the fall of the junta by dropping subtle false hints about what Psychohistory foresees, leading to the Junta making unpopular decisions. However, an agent of the Junta inside Seldon's team, having deduced that Dors is a robot, builds a device that ultimately kills her, leaving Seldon heartbroken. Years later, Seldon discovers that his grand-daughter Wanda has telepathic abilities and begins searching for others like her but fails. Raych eventually decides to move his family to the planet Santanni, but Wanda chooses to remain with her elderly grandfather. However, just after they arrive a rebellion breaks out on the planet and Raych is killed in the fighting. His wife and child are lost when their ship disappears. Seldon eventually finds Stettin Palver, another telepath who becomes Wanda's husband and the pair are eventually instrumental in creating the Second Foundation.
Seldon mentions two indigenous species of Helicon: the lamec and the greti. The first is a hardworking animal, while the latter is dangerous as indicated by the native Helicon saying "If you ride a greti, you find you can't get off; for then it will eat you." The saying is similar to the age-old Chinese proverb "He who rides the tiger finds it difficult to dismount" (騎虎難下), and the words lamec and greti are anagrams of camel and tiger, respectively.
In his old age, he gains the nickname Raven for his dire predictions of the future.
Paul Krugman 
At the 67th science-fiction world convention in Montreal, Paul Krugman, the Nobel Laureate in Economics, mentioned Hari Seldon. According to Krugman, his interest in economics began with Asimov's Foundation novels, in which the social scientists of the future use 'Psychohistory' to attempt to save civilization. Since 'Psychohistory' in Asimov's sense of the word does not exist, Krugman turned to economics, which he considered the next best thing.
- According to the Encyclopedia Galactica (Asimov's fictitious encyclopedia often cited in his future history novels), "It is thought that Seldon's birthdate,which some consider doubtful, may have been adjusted to match that of Cleon's" the last Galactic Emperor of the Entun Dynasty (Prelude to Foundation, p. 3).