| Office: | Ambassador of Nicaragua to the United States |
| Birth Date: | 11 September 1908 |
| Birth Place: | Leon, Nicaragua |
| Death Place: | Potomac, Maryland, United States |
| Spouse: | Lillian Somoza Debayle |
| Occupation: | Judge, president of the lower chamber of National Congress of Nicaragua |
Guillermo Sevilla Sacasa (September 11, 1908, Leon, Nicaragua – December 16, 1997 Potomac, Maryland, United States[1]) was the Nicaraguan ambassador to the United States from 1943 until July 19, 1979, when President Anastasio Somoza Debayle was forced into exile following the Nicaraguan Revolution.[2] As a result of his record-breaking service as ambassador in Washington, D.C., he was appointed Dean of the Diplomatic Corps, a position he held from January 1958 to July 1979.[3]
He was the son of J. Ramón Sevilla Castellón and wife Dolores Sacasa Sacasa, first-cousing of Juan Bautista Sacasa Sacasa and Benjamin Lacayo Sacasa, 63rd and 69th presidents of Nicaragua respectively. Dolores was the daughter of Antioco Sacasa Sarria, brother of Roberto Sacasa Sarria, 44th and 46th President of Nicaragua. Also, her great-uncle was Vicente Cuadra Lugo, 38th President of Nicaragua.
Known as the "world's most decorated ambassador", he was a judge and president of the lower chamber of National Congress of Nicaragua.[4] He also served as Ambassador to the U.S. for 36 years under eight American Presidents and eleven Secretaries of State, a singularly unique and unprecedented achievement, unmatched to this day.
In 1943, Sevilla-Sacasa married Lillian Somoza Debayle, born in León, Nicaragua, on May 3, 1921, the daughter of Anastasio Somoza García, the 65th and 69th President of Nicaragua, and Salvadora Debayle Sacasa, and had nine children.