Donald Kagan (May 1, 1932 – August 6, 2021) was a Lithuanian-born American historian and classicist renowned for his expertise in ancient Greek history. Born in Kuršėnai, Lithuania, he immigrated to the United States at age two with his widowed mother, settling in Brooklyn, New York. Growing up in a working-class immigrant family, he was the first to attend college, graduating from Thomas Jefferson High School where he excelled in football. He earned a bachelor's degree from Brooklyn College (1954) and a master's in classics from Brown University. Kagan began his teaching career at Cornell University before joining Yale University, where he became a prominent figure in the classics and history departments and later professor emeritus. He authored a seminal four-volume history of the Peloponnesian War, establishing himself as one of the foremost scholars of Greek antiquity. Beyond academia, Kagan served as Yale's director of athletics and was a vocal advocate for free expression on campus. As a conservative intellectual, he influenced neoconservative thought, particularly in foreign policy discussions, and was a prominent neoconservative intellectual affiliated with the Hudson Institute, influential in U.S. foreign policy debates. He was known for his impassioned teaching style that inspired generations of students and even shaped Washington strategists during the Reagan era. He was the father of foreign policy expert Robert Kagan. Kagan continued teaching and writing until late in life, receiving accolades for his contributions to education and scholarship, leaving a legacy as a revered educator and historian whose work bridged ancient history with modern political discourse.