Amthor is a surname. Notable people with the surname include:
Carl Ernst August Amthor (1845–1916), German headmaster, solved the Archimedes's cattle problem Christoph Heinrich Amthor (1677–1721), German poet and translator of the Baroque Eduard Gottlieb Amthor (1820–1884), German bookseller and school director Ehrenfried Amthor (1638–1696), senior administrative officer in the Danish army Joachim Ulrich Amthor (1631–1694), Countess-Stolberg Hofrat, Chancellor and Director of the Consistory in Stolberg Philipp Amthor (born 1992), German politician (CDU) Terry K. Amthor (1958–2021), American game designer
William Ramier Amthor (1909–1983), founder of Cost Plus World Market. William Amthor's father opened Amthor Imports in San Francisco in the 1920s. William Amthor and Lincoln Bartlett opened a second store in 1958 (in Fisherman's Wharf), named Cost Plus, which later changed to Cost Plus World Market (today simply World Market).