| Office: | United States Ambassador to Spain |
| President: | Franklin D. Roosevelt |
| Term Start: | 1939 |
| Term End: | 1942 |
| Predecessor: | H. Freeman Matthews Claude G. Bowers |
| Successor: | Carlton J. H. Hayes |
| Office1: | United States Ambassador to Argentina |
| President1: | Franklin D. Roosevelt |
| Term Start1: | 1933 |
| Term End1: | 1938 |
| Predecessor1: | Robert Woods Bliss |
| Successor1: | Norman Armour |
| Birth Date: | 6 April 1876 |
| Birth Place: | Richmond, Virginia |
| Death Place: | Otterville, Missouri |
| Alma Mater: | George Washington University |
Alexander Wilbourne Weddell (April 6, 1876 - January 1, 1948) was an American diplomat. He served as United States ambassador to Argentina from 1933 to 1939 and to Spain from 1939 to 1942.
Weddell was born in Richmond, Virginia, and attended George Washington University. On May 31, 1923, he married a wealthy widow, Virginia Chase Steedman. He served as president of the Virginia Historical Society from 1943 until his death.
Weddell was the author or editor of several books, including:
Weddell and his wife died in a train accident near Otterville, Missouri on January 1, 1948.
The Weddells' Richmond home, Virginia House, was constructed from material from an older house located in Priory Park, Warwick, England. He purchased the Warwick property in 1926 and transported it over two years later. The rebuilt house now belongs to the Virginia Historical Society and is open to the public.