Empress Elisabeth of Austria-Hungary (Sisi) wife of Emperor Franz Joseph was assassinated on September 10, 1898 and her husband died November 21, 1916.
Eleanor of Castile (1241 – November 28, 1290) was Queen of England as the first wife of Edward I of England. Edward outlived her by 17 years and died July 7, 1307.
Matilda of Flanders (c. 1031 – November 2, 1083) was Queen of England and Duchess of Normandy by marriage to William the Conqueror. He died September 9, 1087 and outlived her by 6 years.
Infanta Maria Theresa of Spain the first wife of King Louis XIV of France and Navarre died in July 1683 and her husband survived her by 32 years and died September 1, 1715.
I know that there have been plenty of queens CONSORTS in history whose husbands survived them. Most married queens regnant, however, seem to have become widows -- the most recent examples being Beatrix of the Netherlands, Margrethe II of Denmark, and Elizabeth II of the United Kingdom.
However, there have been exceptions: Isabel I of Castile, Maria II of Portugal, and Juliana of the Netherlands were all outlived by their husbands. Have there been additional examples?