Composers' Nicknames

Franz Joseph Haydn
Papa, for his benevolent authority, as well as for his reputation as the father of the symphony and string quartet. During the 19th century, the nickname was used to trivialize his work as that of a dusty old man. Mozart died too young to gain such a posthumous reputation. Imagine Mozart being Lennon and Haydn being McCartney, in the sense that one of them seems eternally young and vital and the other one's been around so long it's easy to forget he's the same guy who wrote 'Blackird'.

Luigi Boccherini
Haydn's Wife, a dismissive sobriquet assigned after his death, coined by violinist Giuseppe Puppo to describe the mellow charm of the composer's work. Boccherini has enjoyed increased popularity in recent years.

Antonio Vivaldi
The Red Priest, because he was a Venetian priest with red hair. Despite being an ardent Catholic, he withdrew from active priesthood only three years after his ordination, allegedly due to a chest ailment, though probably because he preferred composing. From the Dictionnaire historique des musicians:

One day, when Vivaldi was at Mass, there occurred to him a theme for a fugue. He left the altar immediately, came to his sacristy to write out his theme. Then he returned to the altar to finish his Mass. Brought before an investigation, Vivaldi was excused because he was a musician, that is to say a little mad; and was, moreover, excused from saying Mass in the future.