Which classical composer listed was nicknamed Papa by his contemporaries?

The great classical composer listed above who was nicknamed 'Papa' by his skilled contemporaries was Franz Joseph Haydn (1732–1809). Papa was used as a term of affection. Papa Haydn started out as a term of affection bestowed on Haydn by the musicians who felt that it was an honor to work for him. He was an Austrian composer, and one of the most prolific and prominent composers of the Classical period. He wrote 107 symphonies in total, as well as 83 string quartets, 45 piano trios, 62 piano sonatas, 14 masses, and 26 operas, amongst countless other musical scores.

Haydn had the singular distinction of being called the “Father of the Symphony” and “Father of the String Quartet” because of his important contributions to these genres. He was also instrumental in the development of the piano trio and in the evolution of sonata form. It is well known that his impeccable style of music provided some of the defining sound of the Classical period.

At the end of the day, it was Haydn's key role in classical music, his reputation across Europe, and the wealth of music which he created over his life that earned him the highly esteemed and admired nickname of "Papa Haydn".