Obviously this will be a matter of opinion, but here goes:
Claudio Monteverdi (1567-1643) wrote about 18 operas, but only three complete works survive. Many people recognize L'Orfeo(1607) as the first major Opera to bring together recitative, aria, choral and instrumental numbers in a dramatically effective work. The beautiful aria "Lasciatemi morire" that survives from his L'Arianna (1608) suggests that this opera was also a masterpiece.
Monteverdi's other two surviving operas, Il Ritorno d'Ulisse (Return of Ulysses) and L'Incoronazione di Poppea (Coronation of Poppea) were written in 1640 and 1642 respectively, toward the end of his life. By this time the Baroque style was more firmly established and opera was well on its way toward being the institution we know today, but Monteverdi was still on top of his game. These are really powerful works.
Another point of view might suggest Mozart, however, since his works are the earliest that have remained a part of the repertoire since their premieres. The change from Baroque to Classical opera styles was huge, both in the waning use of the male soprano voice and in the move away from stylized dramatic conventions. He could be called the first great modern opera composer.
A third answer might be Christoph Willibald Von Gluck, whose Orfeo ed Euridice is the earliest opera to hold a place in the standard international repertoire. It premiered in Vienna in 1762.
Mozart, Rossini, Donizetti, Verdi, Wagner, Bizet and Puccini. A few others wrote one (or at most) two magnificent operas, but were not essentially opera composers, and that's a large category. Joplin wrote a brilliant opera - but only one. Gershwin wrote a brilliant opera - but only one, Beethoven wrote a brilliant opera - but only one. You get the idea. The seven listed first were the heavy hitters.
This is Austrian composers Alban Bergs first opera - premièred in 1925. It is normally accepted as possibly the most famous example of atonal [not in any key] opera composition. It is also looked upon as the first 20th century avant garde opera.
The style of music that was rebeled against opera was in this website.
opera house
William Tell Overture
The Phantom of the Opera. On Broadway.
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This is Austrian composers Alban Bergs first opera - premièred in 1925. It is normally accepted as possibly the most famous example of atonal [not in any key] opera composition. It is also looked upon as the first 20th century avant garde opera.
There are many German opera composers. Some of these composers include Ludwig van Beethoven, as well as Carl Maria von Weber.
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Giuseppe Verdi is a famous Italian opera composer.
Britten
Fr. Charley has written: 'The new opera glass' 'The new opera glass: containing the plots of the most popular operas and a short biography of the composers' -- subject(s): Composers, Operas, Stories, plots
beethoven and schumann, i think.
Probably Sydeny Opera House :)
An opera written by the french composer, Georges Bizet.One of his most famous opera's was Carmen.
Sebastian Bach
The style of music that was rebeled against opera was in this website.