Joseph Gregor Werner (bapt. 29 January 1693 Ybbs/Danube Austria, died 3 March 1766 Eisenstadt, Hungary, now Austria) was musical director at the court of the Esterházy family from 1728. For 5 years, from 1761 Joseph Haydn was his — not so much esteemed — vice court musician. The latter, in contrary, published some introductions and fugues of his predecessor in 1804. Werner wrote chamber music, symphonies, a-capella masses and oratories. One of the best known is the "Musicalischer Instrumental-Calender" (a collection of chamber concerts published 1748, portraying each month in 4 or 5 allegoric pieces (signs of the zodiac, length of days and nights, characteristic labours and entertainments etc.). On 3rd march 1766 Gregor Joseph Werner died in the princely residence in Eisenstadt and Haydn became his successor.
(Taken (and translated) from the German text in the Honegger/M. Encyclopedia.)