Isaac Newton
One of the most conspicuous figures in the history of science. In addition to the monumental Principia (Mathematical Principles of Natural Philosophy) and Opticks, he left a tremendous amount of manuscripts on alchemy. This makes him a very complex figure. Anyway, his theories of motion, and of space and time are still one of the main subjects of the philosophy of science.
As is often the case with a great figure, various kinds of myth and exaggeration surround Newton. For instance, he was graduated from Trinity College, Cambridge, in 1665, and then the university was closed (because of plague) and he went back to Woolsthorpe; and it was often told that 1666 was the annus mirabilis (miraculous year) when he formulated most of the basic ideas for his whole work, including the mathematical theory of "fluxions" (now called differential calculus), the laws of motion and gravitation (there is an apple tree in Woolsthorpe), and the theory of optics.
No doubt he must have formed some good ideas; but he must spend many many years for publishing his results, because he must have had to reconsider and work out, in the first place, mere ideas into systematic theories which can stand in the face of facts. And historical studies show that it is quite hard to give credibility to the alleged annus mirabilis.
In the second place, he had to fight for "priority problems". Edmund Halley urged Newton, around 1684 (long after 1666!), to publish his work on motion and Newton was persuaded; but Newton had to work hard again, and moreover he was reminded of the fact that he already had two quarrels with Hooke over the priority (and Newton himself was not a decent person); there arised again a bitter quarrel with Hooke over the priority of the "inverse square law". But Halley managed to succeed in publishing all three books in 1687, and this was the first completed work of Newton; thus Westfall says that this was the turning point for Newton's life (Never at Rest, ch. 10, 1980).
See Newton's Scholium (where he discusses absolute space and time)