Johann Adolph Hasse (March 25, 1699 - December 23, 1783) was a German Classical composer.

Hasse was born at Bergedorf near Hamburg and received his first musical education from his father. Being possessed of a fine tenor voice, he chose a theatrical career and joined the operatic troupe conducted by Reinhard Keiser, in whose orchestra Handel had played the second violin some years before. Hasse's success led to an engagement at the court theatre of Brunswick-Lüneburg, and it was there that, in 1723, he made his debut as a composer with the opera Antigonus. The success of this first work induced the duke to send Hasse to Italy for the completion of his studies, and in 1724 he went to Naples and placed himself under Porpora, with whom, however, he seems to have disagreed both as a man and as an artist. On the other hand he gained the friendship of Alessandro Scarlatti, to whom he owed his first commission for a serenade for two voices, sung at a family celebration of a wealthy merchant by two of the greatest singers of Italy, Farinelli and Signora Tesi.

This event established Hasse's fame; he soon became very popular, and his opera Sesostrato, written for the Royal Opera at Naples in 1726, made his name known all over Italy. At Venice, where he went in 1727, he became acquainted with the celebrated singer Faustina Bordoni, who became the composer's wife in 1730. The two artists soon afterwards went to Dresden, in compliance with a brilliant offer made to them by the splendor-loving elector of Saxony, Augustus II. There Hasse remained for two years, after which he again journeyed to Italy and to London where he was tempted by the aristocratic clique inimical to become the rival and antagonist of Handel. But this he modestly and wisely declined, remaining in London only long enough to superintend the rehearsals for his opera Artaserse (first produced at Venice, 1730).

All this while Faustina had remained at Dresden, the declared favourite of the public and unfortunately also of the elector; nor was her husband, who remained attached to her, allowed to see her except at long intervals. In 1739, after the death of Augustus II, Hasse settled permanently at Dresden till 1763, when he and his wife retired from court service with considerable pensions. But Hasse was still too young to rest on his laurels. He went with his family to Vienna, and added several operas to the great number of his works already in existence. His last work for the stage was the opera Ruggiero (1771), written for the wedding of Archduke Ferdinand of Austria-Este at Milan.

On the same occasion a work by Mozart, then fourteen years old, was performed, and Hasse observed "this youngster will surpass us all." By desire of his wife Hasse settled at her birthplace of Venice, and there he died.

Like other composers of the early to mid eighteenth century, Hasse used small orchestras consisting mainly of strings. In dramatic fire also he was wanting, but he had a fund of gentle and genuine melody, and by this fact his enormous popularity during his life must be accounted for. The two airs which Farinelli had to repeat every day for ten years to the melancholy king of Spain, Philip V, were both from Hasse's works. Of Faustina Hasse it will be sufficient to add that she was, according to the unanimous verdict of the critics (including Dr Burney), one of the greatest singers of a time rich in vocal artists. The year of her death is not exactly known. Most probably it shortly preceded that of her husband.