Michael H. Hart (born April 28, 1932 in New York City) is a Jewish American astrophysicist who has also written three books on history and controversial articles on a variety of subjects. Hart describes himself as a Jeffersonian liberal, while his critics call him a conservative and a racial separatist.

The 100: A Ranking of the Most Influential Persons in History is a 1978 book by Michael H. Hart, reprinted in 1992 with revisions. It is a ranking of the 100 people who, according to Hart, most influenced human history.

Surprising to readers was the first person on Hart's list, Muhammad instead of Jesus or Moses. Hart asserted that Muhammad was "supremely successful" in both the religious and secular realms. He also opined that Muhammad's role in the development of Islam was far more influential than Jesus' collaboration in the development of Christianity. He attributes the development of Christianity to St. Paul, who played a pivotal role in its dissemination.

The 1992 revisions included the demotion of figures associated with Communism, such as Vladimir Lenin and Mao Zedong, and the introduction of Mikhail Gorbachev. Hart took sides in the Shakespearean authorship issue and substituted Edward de Vere, 17th Earl of Oxford for William Shakespeare. Hart also substituted Niels Bohr and Henri Becquerel with Ernest Rutherford, thus correcting an error in the first edition. Henry Ford was also promoted from the "Honorary Mentions" list, replacing Pablo Picasso. Finally, some of the rankings were re-ordered, although no one listed in the top ten changed position.

Hart wrote another book in 1999, entitled A View from the Year 3000, voiced in the perspective of a person from that future year and ranking the most influential people in history. Roughly half of those entries are fictional people from 2000–3000, but the remainder are actual people. these were taken mostly from the 1992 edition, with some re-ranking of order.