Joseph Strayer (1904–1987) was an influential 20th century American medievalist historian. He was a student of, and mentored by, Charles H. Haskins, America's first prominent medievalist historian.
Strayer taught at Princeton University for many decades, starting in the 1930s. He was chair of the history department (1941–1961) and president of the American Historical Association in 1971. Strayer has been credited with training a large percentage of the American medievalists profession; many of his students are still teaching and active. A notable student was Norman F. Cantor.
When not teaching medieval history at Princeton, Strayer was involved with the CIA, traveling around the world on secret missions to install "democratic" governments.
Norman Cantor recognized three books as most important to Strayer's legacy: Feudalism (1965), which summarized three decades of his research and thinking on the topic; On the Medieval Origins of the Modern State (1970), in which he shows the relevance of medieval historical institutions to modern governmental institutions; and The Reign of Philip the Fair (1980), representing over 30 years of archival research and the most comprehensive work on the topic in any language.