Maria Stuarda (Mary Stuart) is a tragic opera (tragedia lirica), in two acts, by Gaetano Donizetti, to a libretto by Giuseppe Bardari, based on Andrea Maffei's translation of Friedrich Schiller's 1800 play Maria Stuart.

The opera is one of a number of operas by Donizetti which deal with the Tudor period in English history, including Anna Bolena (named for Henry VIII's second wife, Anne Boleyn), Roberto Devereux (named for a putative lover of Queen Elizabeth I of England) and Il castello di Kenilworth. The lead female characters of the operas Anna Bolena, Maria Stuarda, and Roberto Devereux are often referred to as the "Three Donizetti Queens". The story is loosely based on the lives of Mary, Queen of Scots (Mary Stuart) and her cousin Queen Elizabeth I. Schiller had invented the confrontation of the two Queens, who in fact never met.

After a series of problems surrounding its presentation in Naples after the final dress rehearsal – including having to be re-written for a totally different location, a different time period, and with Buondelmonte as its new title – Maria Stuarda as we know it today premiered on 30 December 1835 at La Scala in Milan.

In a variety of areas – drama, literature (fiction or otherwise) – England in the Tudor era (and Scotland at the time of Mary Stuart and beyond in particular, Donizetti's own Lucia di Lammermoor being an example) exerted a fascination upon continental Europeans in an extraordinary way. In literature, it has been noted that more than 20,000 books have appeared about Mary's life and that, within two years of her death, stage plays also began to appear. In addition to Schiller's Maria Stuart, there had been another influential play, Count Vittorio Alfieri's Maria Stuarda written in 1778 in which "that unfortunate queen is represented unsuspicious, impatient of contradiction and violent in her attachments."

When it came to what had been handed down about Elizabeth I to Donizetti and other Italian composers, opera stage director Stephen Lawless notes that the continental view would have been very different from the Anglo-centric one of Elizabeth as Good Queen Bess, as Gloriana, and as the one who routed Catholicism from England's shores. But from an Italian perspective, Elizabeth was a heretic and, indeed, a bastard since "her father Henry VIII had never obtained an annulment from the Pope to end his marriage to Catherine of Aragon in order to marry his second wife (Elizabeth's mother) Anne Boleyn" Therefore, to European Catholics, Mary was a martyr and the legitimate ruler of England, a sympathetic character contrasted with Elizabeth, who was traditionally cast in a darker role, often "as unrestrainedly jealous, willful, and easily over-wrought. This is the portrait of Elizabeth found, not too unexpectedly, in Bardari's libretto".

As far as Italian opera of the primo ottocento is concerned, these attitudes found their way into the works which poured forth: they covered a large portion of the Tudor era, including works about Henry VIII's first daughter, Mary, who became Mary I of England, known as "Bloody Mary" for enforcing the country's strict return to Catholicism. The appeal of these operas has been expressed by Professor Alexander Weatherson in the 2009 Donizetti Society Newsletter as follows (with the addition of relevant opera titles associated with the named composers):

But Weatherson concludes:

Having seen Schiller's play in Milan in an Italian translation, Donizetti approached the famed librettist Felice Romani, who had written a successful libretto in 1830 for Anna Bolena, the opera which secured the composer's place as one of the leaders of his day. Wanting a strong and powerful subject for his new work, the composer's idea was to have Romani prepare a libretto about Mary Stuart, but the librettist appears to have ignored him, perhaps because of his desire to get away from writing for the theatre, which he increasingly found to be distasteful.