L'assedio di Calais (The siege of Calais) is an 1836 melodramma lirico, or opera, in three acts by Gaetano Donizetti, his 49th opera. Salvatore Cammarano wrote the Italian libretto, which has been described as "...a remarkable libretto, the closest Cammarano ever got to real poetry, particularly in his description of the embattled city and the heartfelt pride of its citizens". It was based on Luigi Marchionni's play L'assedio di Calais (also called Edoardo III), which had been presented in Naples around 1825, and secondarily on Luigi Henry's ballet L'assedio di Calais, which had been performed in Naples in 1828 and revived in 1835.

Both of these were probably derived from the French play Eustache de St Pierre, ou Le siège de Calais by Hubert (pen name of Philippe-Jacques Laroche), which had been given in Paris in 1822 and was in turn taken from the 1765 play Le siège de Calais by Pierre-Laurent Buirette de Belloy. The historical basis was Edward III's siege of Calais in 1346, toward the beginning of the Hundred Years' War.

The opera was premiered on 19 November 1836 at the Teatro San Carlo in Naples. It was dedicated to the Queen Mother, Maria Isabella. It was the thirteenth of the composer's operas to be given its premiere in that house and it immediately followed the previous year's successful Lucia di Lammermoor there. L'assedio received sixteen performances that season, and, since the opera "met the requirements for a royal occasion, with its happy ending, and had an additional bonus in its glorification of the part played by the English queen, Donizetti duly received the King's congratulations".

By 1840 it had disappeared from the world's stages and it did not re-appear until 1990 at the Donizetti Festival in Bergamo.