Thomas Cahill (1940-2022) was an Irish American popular historian and writer who published six books in a series called Hinges in History for Penguin Random House. How the Irish Saved Civilization is the first in the series. Other monographs in the series include histories of Jewish and Greek contributions to the West, the Italian Renaissance and the Protestant Reformation, and Jesus of Nazareth.

Jesuit priests educated Cahill in the Catholic tradition, and he went on to study classical literature and philosophy at the Catholic Fordham University in New York City. He contemplated joining the priesthood and was awarded a Master of Fine Arts degree in film and dramatic literature from Columbia University. In addition to reading Greek and Latin, Cahill also read Hebrew, Italian, French, and German. His language skills prepared him to translate and analyze the primary sources upon which his popular histories rely. He was a visiting scholar at the Jewish Theological Seminary of America and taught at several universities, including Fordham, Seton Hall University, and Queens College-CUNY. He also lived in Ireland for a year and a half while researching a guidebook on the country, which he coauthored with his wife, Susan. He also worked as the Director for Religious Publishing at Doubleday and as a book reviewer for The Los Angeles Times.