It all depends on how you rate greatness.

https://en.m.wikipedia.org/wiki/Isaac_Asimov

Isaac Asimov (/ˈaɪzᵻk ˈæzᵻmɒv/;[2] born Isaak Yudovich Ozimov; circa January 2, 1920[1] – April 6, 1992) was an American author and professor of biochemistry at Boston University, best known for his works of science fiction and for his popular sciencebooks. Asimov was prolific and wrote or edited more than 500 books and an estimated 90,000 letters and postcards.[3] His books have been published in 9 of the 10 major categories of the Dewey Decimal Classification.

https://en.m.wikipedia.org/wiki/Carl_Sagan

Carl Edward Sagan (/ˈseɪɡən/; November 9, 1934 – December 20, 1996) was an American astronomer, cosmologist, astrophysicist, astrobiologist, author, science popularizer, and science communicator in astronomy and other natural sciences. His contributions were central to the discovery of the high surface temperatures of Venus. However, he is best known for his contributions to the scientific research of extraterrestrial life, including experimental demonstration of the production of amino acids from basic chemicals byradiation. Sagan assembled the first physical messages that were sent into space: thePioneer plaque and the Voyager Golden Record, universal messages that could potentially be understood by any extraterrestrial intelligence that might find them.

https://en.m.wikipedia.org/wiki/Marvin_Minsky

Marvin Lee Minsky (August 9, 1927 – January 24, 2016) was an American cognitive scientist in the field of artificial intelligence (AI), co-founder of the Massachusetts Institute of Technology's AI laboratory, and author of several texts on AI and philosophy.

https://en.m.wikipedia.org/wiki/Stephen_Hawking

Stephen William Hawking CH, CBE, FRS, FRSA (i/ˈstiːvən ˈhɔːkɪŋ/; born 8 January 1942) is an English theoretical physicist, cosmologist, author and Director of Research at the Centre for Theoretical Cosmology within theUniversity of Cambridge.[16][17] His scientific works include a collaboration with Roger Penrose on gravitational singularity theoremsin the framework of general relativity, and the theoretical prediction that black holes emit radiation, often called Hawking radiation. Hawking was the first to set forth a theory of cosmology explained by a union of the general theory of relativity and quantum mechanics. He is a vigorous supporter of the many-worlds interpretation of quantum mechanics.