Apollo et Hyacinthus seu Hyacinthi metamorphosis (Latin for Apollo and Hyacinth or The Metamorphosis of Hyacinth), K. 38, is an opera in three acts written in 1767 by Wolfgang Amadeus Mozart, who was 11 years old at the time. It is Mozart's first true opera (when one considers that Die Schuldigkeit des ersten Gebots is simply a sacred drama). As is suggested by the name, the opera is based upon the Greek myth of Hyacinth and Apollo as told by Roman poet Ovid in his Metamorphoses. Interpreting this work, Rufinus Widl wrote the libretto in Latin.

Ascanio in Alba, K. 111, is a pastoral opera in two parts (Festa teatrale in due parti) by Wolfgang Amadeus Mozart to an Italian libretto by Giuseppe Parini. It was commissioned by the Empress Maria Theresa for the wedding of her son, Archduke Ferdinand Karl, to Maria Beatrice d'Este on 15 October 1771.

Bastien und Bastienne (Bastien and Bastienne), K. 50 (revised in 1964 to K. 46b) is a one-act singspiel, a comic opera, by Wolfgang Amadeus Mozart. Bastien und Bastienne was one of Mozart's earliest operas, written in 1768 when he was only twelve years old. It was allegedly commissioned by Viennese physician and 'magnetist' Dr. Franz Mesmer (who himself would later be parodied in Così fan tutte) as a satire of the 'pastoral' genre then prevalent, and specifically as a parody of the opera Le devin du village by Jean-Jacques Rousseau. The German libretto is by Friedrich Wilhelm Weiskern, Johann Heinrich Friedrich Müller and Johann Andreas Schachtner, based on Les Amours de Bastien et Bastienne by Justine Favart and Harny de Guerville. After its supposed premiere in Mesmer's garden theater (that is only corroborated by an unverified account of Nissen), it was not revived again until 1890. It is not clear whether this piece was performed in Mozart's lifetime. The first known performance was on 2 October 1890 at Architektenhaus in Berlin. The opera is written in both the French and German manners. Many of the melodies are French in manner, but Bastienne's first aria is a true German lied. This melody is also used in Mozart's Trio in G for Piano, Violin and Violoncello, K. 564 (1788). Another purely German lied is Bastienne's aria "I feel certain of his heart". Mozart utilizes the orchestra sparingly, with the exception of the reconciliation scene. The opening theme of Mozart's overture resembles that of the first movement of Beethoven's Symphony no. 3, Eroica (in a different key). It is unlikely that Beethoven was familiar with Mozart's youthful opera. In any case, opening a movement with an arpeggio of the tonic chord was an extremely common occurrence in the Classical period. The resemblance is likely coincidental. Although he was very young, Mozart already had excellent vocal writing skills and a knack for parody and whimsy which would reach full flower in his later works. Bastien und Bastienne is possibly the easiest to perform of Mozart's juvenile works.

Così fan tutte, ossia La scuola degli amanti (Women are like that, or The School for Lovers), K. 588, is an opera buffa in two acts by Wolfgang Amadeus Mozart. It was first performed on 26 January 1790 at the Burgtheater in Vienna, Austria. The libretto was written by Lorenzo Da Ponte who also wrote Le nozze di Figaro and Don Giovanni. Although it is commonly held that Così fan tutte was written and composed at the suggestion of the Emperor Joseph II, recent research does not support this idea. There is evidence that Mozart's contemporary Antonio Salieri tried to set the libretto but left it unfinished. In 1994, John Rice uncovered two terzetti by Salieri in the Austrian National Library. The short title, Così fan tutte, literally means "So do they all", using the feminine plural (tutte) to indicate women. It is sometimes translated into English as "Women are like that". The words are sung by the three men in act 2, scene 3, just before the finale; this melodic phrase is also quoted in the overture to the opera. Da Ponte had used the line "Così fan tutte le belle" earlier in Le nozze di Figaro (in act 1, scene 7).

Don Giovanni (Italian pronunciation: [ˈdɔn dʒoˈvanni]; K. 527; full title: Il dissoluto punito, ossia il Don Giovanni, literally 'The Rake Punished, or Don Giovanni') is an opera in two acts with music by Wolfgang Amadeus Mozart to an Italian libretto by Lorenzo Da Ponte. Its subject is a centuries-old Spanish legend about a libertine, Don Juan, as told by playwright Tirso de Molina in his 1630 play El burlador de Sevilla y convidado de piedra. It is a dramma giocoso blending comedy, melodrama and supernatural elements (although the composer entered it into his catalogue simply as opera buffa). It was premiered by the Prague Italian opera at the National Theatre (of Bohemia), now called the Estates Theatre, on 29 October 1787. Don Giovanni is regarded as one of the greatest operas of all time and has proved a fruitful subject for commentary in its own right; critic Fiona Maddocks has described it as one of Mozart's "trio of masterpieces with librettos by Da Ponte".

Idomeneo, re di Creta ossia Ilia e Idamante (Italian for Idomeneus, King of Crete, or, Ilia and Idamante; usually referred to simply as Idomeneo, K. 366) is an Italian-language opera seria by Wolfgang Amadeus Mozart. The libretto was adapted by Giambattista Varesco from a French text by Antoine Danchet, based on a 1705 play by Crébillion père, which had been set to music by André Campra as Idoménée in 1712. Mozart and Varesco were commissioned in 1780 by Karl Theodor, Elector of Bavaria for a court carnival. He probably chose the subject, though it may have been Mozart. The work premiered on 29 January 1781 at the Cuvilliés Theatre in Munich, Germany.

Il re pastore (The Shepherd King) is an opera, K. 208, written by Wolfgang Amadeus Mozart to an Italian libretto by Pietro Metastasio, edited by Giambattista Varesco. It is an opera seria. The opera was first performed on 23 April 1775 in Salzburg in the Rittersaal (knight's hall) of the Residenz-Theater in the palace of the Archbishop Count Hieronymus von Colloredo. In 1775 the opera was commissioned for a visit by the Archduke Maximilian Francis of Austria, the youngest son of Empress Maria Theresa, to Salzburg. Mozart spent six weeks working on the opera. It consists of two acts and runs for approximately 107 minutes. Metastasio wrote the libretto in 1751, basing it on a work by Torquato Tasso called Aminta. The libretto was picked up when Mozart (just 19 at the time) and his father saw a performance of it set to music composed by Felice Giardini – Mozart's version, however was two acts rather than Giardini's three, and has a few substantial changes. Each act lasts for around an hour in performance. The Salzburg court chaplain Varesco was largely responsible for this editing of Metastasio's libretto. It is often referred to not as an opera, but as a serenata, a type of dramatic cantata. The appearance of a quartet of lovers (Aminta and Elisa, Agenore and Tamiri) of somewhat dubious fidelity automatically puts a modern audience in mind of the later Così fan tutte. The principal psychological theme of the opera is, however, the demands of love against the demands of kingship, as Aminta, the shepherd-king, tussles with his conscience, and in this Il re pastore is closer in theme to Idomeneo than any other of Mozart's operas. Indeed, Idomeneo was the next completed opera that Mozart wrote after Il re pastore, after his six-year-long break from the stage. Furthermore, the theme of qualities for kingship appears in another opera, La clemenza di Tito, his last one.

Il sogno di Scipione, K. 126, is a dramatic serenade in one act (azione teatrale) composed by Wolfgang Amadeus Mozart to a libretto by Pietro Metastasio, which is based on the book Somnium Scipionis by Cicero; Metastasio's libretto has been set to music several times. Mozart had originally composed the work at the age of 15 for his patron, Prince-Archbishop Sigismund von Schrattenbach. After the bishop's death before it could be performed, Mozart dedicated it to Schrattenbach's successor, Count Colloredo. It was given a private performance in the Archbishop's Palace in Salzburg on 1 May 1772, although not in its entirety. Only one aria, the final chorus and the recitative dedicating it to the new Prince-Archbishop were performed. It is highly unlikely that it was ever performed in its entirety in Mozart's lifetime.

L'oca del Cairo (The Goose of Cairo or The Cairo Goose, K. 422) is an incomplete Italian opera buffa in three acts, begun by Wolfgang Amadeus Mozart in July 1783 but abandoned in October. The complete libretto by Giambattista Varesco remains. Mozart composed seven of the ten numbers of the first act, plus some recitative, as well a sketch for a further aria; the extant music amounts to about 45 minutes. The autograph manuscript of the opera is preserved in the Berlin State Library.

La clemenza di Tito (The Clemency of Titus), K. 621, is an opera seria in two acts composed by Wolfgang Amadeus Mozart to an Italian libretto by Caterino Mazzolà, after Pietro Metastasio. Mozart completed the work in the midst of composing Die Zauberflöte, his last opera. La clemenza di Tito premiered on 6 September 1791 at the Estates Theatre in Prague.

La finta giardiniera ("The Pretend Garden-Girl"), K. 196, is an Italian-language opera by Wolfgang Amadeus Mozart. Mozart wrote it in Munich in January 1775 when he was 18 years old and it received its first performance on 13 January at the Salvator Theater in Munich. There is debate over the authorship of the libretto, written for Anfossi's opera the year before. It is often ascribed to Calzabigi, but some musicologists now attribute it to Giuseppe Petrosellini, though again it is questioned whether it is in the latter's style. In 1780 Mozart converted the opera into a German Singspiel called Die Gärtnerin aus Liebe (also Die verstellte Gärtnerin), which involved rewriting some of the music. Until a copy of the complete Italian version was found in the 1970s, the German translation was the only known complete score.

La finta semplice (The Fake Innocent), K. 51 (46a) is an opera buffa in three acts for seven voices and orchestra, composed in 1768 by then 12-year-old Wolfgang Amadeus Mozart. Young Mozart and his father Leopold were spending the year in Vienna, where Leopold was trying to establish his son as an opera composer. He was acting on a suggested request from the Emperor Joseph II that the young boy should write an opera. Leopold chose an Italian libretto by the Vienna court poet Marco Coltellini, which was based on an early work by Carlo Goldoni. During rehearsals, the opera was the victim of intrigues from competing composers claiming that the work was not from the 12-year-old boy, but from his father. Threatened with a sabotaged first night by the impresario Giuseppe Affligio, Leopold prudently decided to withdraw. The opera was never staged in Vienna. It was probably performed the following year in Salzburg at the request of the Prince-Archbishop. Mozart produced a full score of three acts, 26 numbers, in a manuscript of 558 pages. It includes an overture/Sinfonia, one coro, one duet, three ensembles (at the end of each act), and 21 arias. The opera was recorded in its entirety by Leopold Hager for Orfeo in January 1983 with Helen Donath and Teresa Berganza, a performance lasting two hours 45 minutes. Another recording was made in November 1989, with Barbara Hendricks and Ann Murray, and conducted by Peter Schreier. This version was selected by Philips to be part of The Complete Mozart Edition of all the works of Mozart, published in 1991. However, since its premiere in 1769, the opera was not staged until modern times. It was given in March 1985 at the Bloomsbury Theatre as part of the Camden Festival conducted by Nicholas Cleobury, directed by Robert Carsen, with Patricia Rozario, Glenn Winslade and Janis Kelly among the cast. It was performed at the 2006 Salzburg Festival, as part of the production of all of 22 Mozart's operas. The performances were published in the collection of DVDs known as M-22 by Deutsche Grammophon.

The Marriage of Figaro (Italian: Le nozze di Figaro, pronounced [le ˈnɔttse di ˈfiːɡaro] ), K. 492, is a commedia per musica (opera buffa) in four acts composed in 1786 by Wolfgang Amadeus Mozart, with an Italian libretto written by Lorenzo Da Ponte. It premiered at the Burgtheater in Vienna on 1 May 1786. The opera's libretto is based on the 1784 stage comedy by Beaumarchais, La folle journée, ou le Mariage de Figaro ("The Mad Day, or The Marriage of Figaro"). It tells how the servants Figaro and Susanna succeed in getting married, foiling the efforts of their philandering employer Count Almaviva to seduce Susanna and teaching him a lesson in fidelity. Considered one of the greatest operas ever written, it is a cornerstone of the repertoire and appears consistently among the top ten in the Operabase list of most frequently performed operas. In 2017, BBC News Magazine asked 172 opera singers to vote for the best operas ever written. The Marriage of Figaro came in first out of the 20 operas featured, with the magazine describing it as being "one of the supreme masterpieces of operatic comedy, whose rich sense of humanity shines out of Mozart's miraculous score".

Les petits riens (French for "The Little Nothings") is a ballet in one act and three tableaux by Jean-Georges Noverre, with music by Wolfgang Amadeus Mozart and other unknown composers, first performed at the Academie Royale de Musique in Paris on 11 June 1778. The three tableaux are described in the Journal de Paris: l' Amour pris au filet et mis en cage. "Love caught in a net and put in a cage", performed by Mme Guimard, Auguste Vestris and a young child. Jeu de Colin-Maillard. The story of Jean Colin-Maillard was a legend about a warrior who fought on even with his eyes poked out. His name is the French word for the game Blind man's buff. The main role in this scene was performed by Jean Dauberval. Such playful scenery usually had flirtatious connotations, which is famously depicted by Fragonard in his painting Le Collin-Maillard. Espieglerie de l'Amour. "Playfulness of love" is a pastoral scene about a woman, played by Mlle Asselin, disguised as a male shepherd. Two other shepherdesses, performed by Mlles Guimard and Allard, fall in love with the shepherd. Finally, to disenchant the two shepherdesses the imposter ends up revealing her breasts to them. While Mozart was staying in Paris, Noverre asked him to compose a new score for a ballet that he had created in Vienna in 1767. The ballet was to be danced as an interlude in the new opera Le finte gemelle (1771) by Niccolò Piccinni. The opera was a flop and closed after four performances. Although the ballet music was well-received, Mozart was not credited with it, and he was at the time little known in Paris. The score, catalogued as K. Anh. 10/299b, was thought lost, but it was rediscovered in the Paris Opera's archives in the late 19th century and has since entered both the ballet and symphonic repertoire. The Passepied (nr. 11) in D major is reminiscent of the first movement of Tchaikovsky's Souvenir de Florence, Op. 70; a D minor version of the melody appears in bars 5 and 6. The motive derived from this is used throughout the piece. The German musicologist Ernst Fritz Schmid has proposed that the Gavotte in B-flat major, K. 300, was originally intended as an inserted movement of Les petits riens. Written between May and June 1778, Schmid sees no other reason why the composer would have composed stand-alone dance music in Paris whilst he was already writing a ballet. The piece was subsequently laid aside for unknown reasons.

Lo sposo deluso, ossia La rivalità di tre donne per un solo amante (The Deluded Bridegroom, or The Rivalry of Three Women for One Lover) is a two-act opera buffa, K. 430, composed by Wolfgang Amadeus Mozart between 1783 and 1784. However, the opera was never completed and only a 20-minute fragment from act 1 exists.

Lucio Silla (Italian: [ˈluːtʃo ˈsilla]), K. 135, is an Italian opera seria in three acts composed by Wolfgang Amadeus Mozart at the age of 16. The libretto was written by Giovanni de Gamerra, revised by Pietro Metastasio. It was first performed on 26 December 1772 at the Teatro Regio Ducale in Milan and was regarded as "a moderate success". Handel's opera Silla (1713) covered the same subject. Other operas with the same title were also composed by Leonardo Vinci (1723), Pasquale Anfossi (1774), and Johann Christian Bach (1776).

Mitridate, re di Ponto (Mithridates, King of Pontus), K. 87 (74a), is an opera seria in three acts by the young Wolfgang Amadeus Mozart. The libretto is by Vittorio Amedeo Cigna-Santi, after Giuseppe Parini's Italian translation of Jean Racine's play Mithridate. Mozart wrote Mitridate while touring Italy in 1770. The musicologist Daniel E. Freeman has demonstrated that it was composed with close reference to the opera La Nitteti by Josef Mysliveček. The latter was the opera being prepared for production in Bologna when Mozart met Mysliveček for the first time with his father in March 1770. Mysliveček visited the Mozarts frequently in Bologna during the summer of 1770 while Wolfgang was working on Mitridate. Mozart gained expertise in composition from his older friend and also incorporated some of his musical motifs into his own operatic setting. The opera was first performed at the Teatro Regio Ducale, Milan, on 26 December 1770 (at the Milan Carnival). It was a success, performed 21 times despite doubts because of Mozart's extreme youth – he was fourteen at the time. No revival took place until the 20th century. The opera features virtuoso arias for the principal roles, but only two ensemble numbers: the act 2 ending duet between Aspasia and Sifare ("Se viver non degg’io"), and the brief quintet that ends the opera in a manner characteristic of standard baroque opera seria where the opera ends with a short coro or tutti number.

Die Entführung aus dem Serail (German: [diː ʔɛntˈfyːʁʊŋ ʔaʊs dɛm zeˈʁaɪ]) (K. 384; The Abduction from the Seraglio; also known as Il Seraglio) is a singspiel in three acts by Wolfgang Amadeus Mozart. The German libretto is by Gottlieb Stephanie, based on Christoph Friedrich Bretzner's Belmont und Constanze, oder Die Entführung aus dem Serail. The plot concerns the attempt of the hero Belmonte, assisted by his servant Pedrillo, to rescue his beloved Constanze from the seraglio of Pasha Selim. The work premiered on 16 July 1782 at the Vienna Burgtheater, with the composer conducting.

The Magic Flute (German: Die Zauberflöte, pronounced [diː ˈtsaʊbɐˌfløːtə] ), K. 620, is an opera in two acts by Wolfgang Amadeus Mozart to a German libretto by Emanuel Schikaneder. It is a Singspiel, a popular form that included both singing and spoken dialogue. The work premiered on 30 September 1791 at Schikaneder's theatre, the Freihaus-Theater auf der Wieden in Vienna, just two months before Mozart's death. It was Mozart's last opera. It was an outstanding success from its first performances, and remains a staple of the opera repertory. In the opera, the Queen of the Night persuades Prince Tamino to rescue her daughter Pamina from captivity under the high priest Sarastro; instead, he learns the high ideals of Sarastro's community and seeks to join it. Separately, then together, Tamino and Pamina undergo severe trials of initiation, which end in triumph, with the Queen and her cohorts vanquished. The earthy Papageno, who accompanies Tamino on his quest, fails the trials completely but is rewarded anyway with the hand of his ideal female companion Papagena.

Zaide (originally, Das Serail) is an unfinished German-language opera, K. 344, written by Wolfgang Amadeus Mozart in 1780. Emperor Joseph II, in 1778, was in the process of setting up an opera company for the purpose of performing German opera. One condition required of the composer to join this company was that he should write a comic opera. At Salzburg in 1779 Mozart began work on a new opera (now known as Zaide although Mozart did not give it such a title). It contains spoken dialogue, which also classifies it as a Singspiel (literally, "singing play"). Only the arias and ensembles from the first two acts were composed. Missing are an overture and third act. It was popular at the time for operas to depict the rescue of enslaved Westerners from Muslim courts, since Muslim pirates were preying on Mediterranean shipping, particularly to obtain slaves for various purposes. This story portrays Zaide's effort to save her beloved, Gomatz. Mozart was composing for a German libretto by Johann Andreas Schachtner, set in Turkey, which was the scene of his next, completed rescue Singspiel (Die Entführung aus dem Serail). He soon abandoned Zaide, to work on Idomeneo, and never returned to the project. The work was lost until after his death, when Constanze Mozart, his wife, found it in his scattered manuscripts in 1799. The fragments would not be published until 1838, and its first performance was held in Frankfurt on January 27, 1866, the 110th anniversary of Mozart's birth. Zaide has since been said to be the foundations of a masterpiece, and received critical acclaim. The tender soprano air, "Ruhe sanft, mein holdes Leben" is the only number that might be called moderately familiar. The title Zaide was supplied by the Mozart researcher Johann Anton André, who first published the score, including his own completion of it, in the 1830s. André's father Johann André had set the same text to music, before Mozart commenced his singspiel. Modern companion pieces to Zaide have been written by both Luciano Berio and Chaya Czernowin. In modern performances, Mozart's Symphonies No. 26, K. 184, or No. 32, K. 318 – which was composed around the same time as Zaide and later used as an overture to Francesco Bianchi's La villanella rapita (1784) – are often given as an overture to Zaide. Completions of the opera may use a pastiche of Mozart's concert arias or, more popularly, music from Thamos, King of Egypt, also from the same period of Mozart's career.