Roberto Devereux (in full Roberto Devereux, ossia Il conte di Essex, Italian: [roˈbɛrto deveˈrø osˈsiːa il ˈkonte di ˈɛsseks]; "Robert Devereux, or the Earl of Essex") is an 1837 tragedia lirica (tragic opera) in three acts by Gaetano Donizetti. The opera is loosely based on the life of Robert Devereux, 2nd Earl of Essex, an influential member of the court of Queen Elizabeth I of England.

Salvadore Cammarano wrote the Italian-language libretto based on François Ancelot's French tragedy Elisabeth d'Angleterre (Paris, 1832), with some of the text taken from Felice Romani's libretto for Saverio Mercadante's opera Il conte d'Essex (Milan, 1833), also based on Ancelot's play. Cammarano's libretto also incorporated elements from the 1787 French play Histoire secrète des amours d'Elisabeth et du comte d'Essex (1787) by Jacques Lescène des Maisons. Devereux was the subject of at least two earlier French plays, both titled Le Comte d'Essex: one in 1638 by Gauthier de Costes, seigneur de la Calprenède, and one in 1678 by Thomas Corneille.

It is one of a number of operas by Donizetti which deal with the Tudor period of English history and which include Anna Bolena (about Anne Boleyn), Maria Stuarda (about Mary, Queen of Scots) and Il castello di Kenilworth. The lead female characters – Anne Boleyn, Mary Stuart and Elizabeth herself – have been referred to as the "Three Donizetti Queens." They became popular in the 1970s, when the American soprano Beverly Sills promoted them as a series at New York City Opera.

It has been said that, "although the plot plays fast and loose with history, the opera carries its own brand of dramatic conviction".

The contract for a new opera seria for the Teatro San Carlo in Naples was concluded in spring 1837. The generation of Roberto Devereux was overshadowed by serious crises in the life of the composer. During the previous year, Donizetti had lost both his parents and then his wife Virginia Vaselli delivered a stillborn baby. In June 1837, another child died during birth. On 30 July, his wife died at the age of 28. Rehearsals for the premiere began at the end of August 1837; most of the score had to be written in the month following his wife's death. Additionally, a cholera epidemic delayed again the start of rehearsals.

Salvatore Cammarano's libretto is very truthful to Jacques-François Ancelot's tragedy, a romantic rewrite of the material already dealt with by Pierre Corneille and La Calprenède in France, to which he added individual touches from Lescènes's Histoire. The plot is hardly original, mainly derived from Felice Romani's libretto Il Conte d'Essex of 1833, originally set by Saverio Mercadante. Romani's widow charged Cammarano with plagiarism; the practice of stealing plots was very common between rival Italian opera houses.

19th century

Roberto Devereux was first performed on 28 October 1837 at the Teatro di San Carlo, Naples. Within a few years, the opera's success had caused it to be performed in most European cities including Paris on 27 December 1838, for which he wrote an overture which quoted, anachronistically, "God Save the Queen"; London on 24 June 1841; Rome in 1849; Palermo in 1857; in Pavia in 1859 and 1860; and in Naples on 18 December 1865. Also, it was given in New York on 15 January 1849, but it would appear that after 1882, no further performances were given during the 19th century.