Henry Raup Wagner (September 27, 1862 – March 27, 1957) was an American book collector, bibliographer, cartographer, historian, and business executive. He was the author of over 170 publications, including books and scholarly essays, mainly about the histories of the American frontier and the Spanish exploration and colonization of Mexico. He also assembled tens of thousands of books and manuscripts and formed several collections from them.
Wagner was born in Philadelphia, Pennsylvania, on September 27, 1862. He graduated from Yale University in 1884 and then from Yale Law School in 1886. He went west and began settling in places like Kansas City and then Denver, where he became involved in the mining business. One of his first employers was the Globe Smelting and Refining Company. In 1892 they assigned him to Mexico where he began collecting books on metallurgy and became interested in the history of the region. From 1898, he began working for the Guggenheim family, who transferred him to Chile and then to New York. In 1903, he became the manager of their London office where he collected many more books on different subjects, including South American history and economics. The latter became the subject of his first bibliography, Irish Economics: 1700–1783. From 1906 to 1915, he managed the Guggenheims' affairs in Mexico, and was then transferred to Chile where he studied in writer José Toribio Medina's residence. By then Wagner was transitioning from book collecting to research and writing, and sold his large Mexican collection to the Yale University Library.
He published The Plains and the Rockies in 1920 and quit his job the following year. Wagner helped revive the California Historical Society in 1922 and sold his last major book collection that year to the Huntington Library. The Spanish Southwest, 1542–1794 was published in 1924, and Sir Francis Drake's Voyage Around the World, Its Aims and Achievements in 1926. He became interested in cartography around that time and worked for several years on that subject. The Cartography of the Northwest Coast of America to the Year 1800 was published in 1937. Later, between 1942 and 1944, Wagner wrote a series of books on 16th century Spanish conquistadors, notably Hernán Cortés who was the subject of The Rise of Fernando Cortés.
Wagner married Blanche Henriette Collet in 1917. They initially settled in Berkeley, California, but after 1928 they lived in San Marino, California. He died on March 27, 1957, aged 94. The California Historical Society established the Henry R. Wagner Memorial Award in 1959.