Elizabeth Patterson (1785-1879) married Napoleon's brother Jerome Bonaparte (1784-1860), later King of Westphalia, in 1803; the marriage was annulled in 1805, but they had a son who founded an American line of Bonapartes that flourished (with some distinction) until 1945.
Agnes Leclerc Joy (1844-1912) married Prince Felix of Salm-Salm (1828-1870), a general in the U.S. and Imperial Mexican armies, in 1862.
Alice Heine (1858-1925) married Prince Albert I of Monaco (1848-1922) in 1889; they separated in 1902 but never divorced.
Anita Stewart (1885-1977) married Prince Miguel of Braganza (1878-1923), eldest son of the Miguelist pretender to the Portuguese throne, in 1909. The marriage was originally accepted as dynastic but Miguel and his father (also Miguel) renounced their rights in favor of his younger half-brother Duarte (father of the current pretender) in 1920.
Daria Pankhurst Wright Pratt (1859-1938) married Prince Alexis Karageorgevich of Serbia (1859-1920) in 1913.
Nevada Stoody Hayes (1885-1941) married Prince Afonso of Portugal (1865-1920), uncle of the deposed King Manoel II, in 1917.
None May "Nancy" Stewart Worthington Leeds (1878-1923) married Prince Christopher of Greece (1888-1940), youngest son of King George I, in 1920; she was granted the title "Princess Anastasia of Greece." Her son from her first marriage, William B Leeds, then married into royalty as well, wedding his new stepfather's niece Princess Xenia of Russia.
Audrey Emery (1904-1971) married Grand Duke Dmitri of Russia (1891-1942) in 1926; they divorced in 1937 having had one son, Paul Ilyinsky (1928-2004) who eventually served as Mayor of Palm Beach, Florida.
Margaret Watson (1899-1993) married Prince Charles Philippe of Orléans, Duc de Nemours, de Vendôme et d'Alençon (1905-1970) in 1928.
Wallis Warfield Simpson (1896-1986) married the former King Edward VIII (1894-1972), who had famously abdicated the British throne for her, in 1937, becoming the Duchess of Windsor.
Alice Eilken (1923-1996) married Prince Rostislav of Russia (1902-1978) in 1944.
Grace Kelly (1929-1982) married Albert I's great-grandson Prince Rainier III of Monaco (1923-2005) in 1956.
Julia Mullock (b 1928) married Gu, Prince of Korea (1931-2005) in 1959; childless, they divorced in 1982.
Joan Douglas Dillon (b 1935), daughter of U.S. Treasury Secretary C. Douglas Dillon, married Prince Charles of Luxembourg (1927-1977) in 1967.
Hope Cooke (b 1940) married Palden Thondup Namgyal (1923-1982), the last King of Sikkim (1963-75) in 1963. Sikkim was annexed by India in 1975 and they divorced in 1980.
Lisa Halaby (b 1951) married King Hussein of Jordan (1935-1999) in 1978, becoming Queen Noor.
Marie-Chantal Miller (b 1968) married Crown Prince Pavlos of Greece (b 1967) in 1995.
Kathleen Walker (b 1986) married Archduke Imre of Austria (b 1985) in 2012.
Ariana Austin (b 1984) married Ethiopia's Prince Joel Dawit Makonnen (b 1982) in 2017.
Meghan Markle (b 1981) married Britain's Prince Harry (b 1984) in 2018.
Unofficial Royalty: Americans Who Married Royalty