DICTIONARY DEFINITION:
"an extended dramatic composition, in which all parts are sung to instrumental accompaniment, that usually includes arias, choruses, and recitatives, and that sometimes includes ballet" -
http://www.dictionary.com/browse/opera
ORIGINS:
"Ballet and Opera were born out of royal entertainments in 17th-century Italy and France. They were unashamed propaganda aimed at impressing foreign dignitaries and other royals. The stories or themes were taken from classical mythology, drawing parallels between the ruler and the mythological gods or heroes." - http://www.vam.ac.uk/content/articles/t/early-opera/
FIRST OPERA:
"The first opera was Daphne, first performed in 1598 during Carnival at the home of Jacopo Corsi (d.1604) in Florence, music by Corsi and Jacopo Peri (1561-1633), libretto by Ottavio Rinuccini (1562-1621). It is recognized as the first because it was the first of a series of similar pieces which established the form of early 17th century Italian opera, and all subsequent developments were based on that tradition. The score does not survive." - http://www.medieval.org/emfaq/misc/opera.html
COMPOSERS:
Corsi (1561 - 1602) & Peri (1561 - 1633) - http://www.hoasm.org/IVD/Corsi.html
Bach (1685 - 1750) // Mozart (1756 - 1791) // Beethoven (1770 - 1827) // Verdi (1813 - 1901) // Tchaikovsky (1840 - 1893) // Chopin (1810 - 1849) // Vivaldi (1678 - 1741) // Puccini (1858 - 1924) // Handel (1685 - 1759) // Stravinsky (1882 - 1971) - http://historylists.org/people/top-10-most-famous-classical-music-composers.html
PERFORMERS:
Lind (1820 - 1887) - https://en.wikipedia.org/wiki/Jenny_Lind & http://www.vam.ac.uk/content/articles/0-9/19th-century-opera/
Schwarzkopf (Soprano) (1915 - 2006) // Geda (Tenor) (1925 - ) // Price (Soprano) (1927 - ) // Wunderlich (Tenor) (1930 - 1966) // Flagstad (Soprano) (1895 - 1962) // Pavarotti (Tenor) (1935 - 2007) // Sutherland (Soprano) (1926 - 2010) // Domingo (Tenor) (1941 - ) // Callas (Soprano) (1923 - 1977) // Fischer-Dieskau (Baritone) (1925 - ) - http://listverse.com/2012/04/08/top-10-greatest-opera-singers/
I researched Opera as it was heavily influential on musical theatre we know today. Some opera does technically count as musical theatre as it obviously involves singing, acting (through song) and sometimes dancing. The musical "Rent" (by Jonathon Larson) was loosely based on Puccini's opera "La Bohéme". Opera was also influential with its use of lavish costumes and comical songs (such as "Mein Herr Marquis" from "Die Fledermaus").
