Johann Adam Hiller (25 December 1728, Wendisch-Ossig, Saxony – 16 June 1804, Leipzig) was a German composer, conductor and writer on music, regarded as the creator of the Singspiel, an early form of German opera. In many of these operas he collaborated with the poet Christian Felix Weiße.
Furthermore, Hiller was a teacher who encouraged musical education for women, his pupils including Elisabeth Mara and Corona Schröter. He was Kapellmeister of Abel Seyler's theatrical company, and became the first Kapellmeister of Leipzig Gewandhaus.
By the death of his father in 1734, Hiller was left dependent to a large extent on the charity of friends. He came from a musical family, and also learned the basics of music from a school master in his home town, Wendisch-Ossig. From 1740 to 1745, he was a student at the Gymnasium in Görlitz, where his fine soprano voice earned him free tuition. In 1746 he went to study at the famous Kreuzschule in Dresden. There he took keyboard and basso continuo lessons with Gottfried August Homilius.
In 1751, he enrolled in the University of Leipzig to study law, supporting himself by giving music lessons, and also by performing at concerts both on the flute and as a vocalist. Hiller immersed himself in the rich musical life of the town, and gradually adopted music as his sole profession. He took an active role in the Großes Concert, which was the leading concert undertaking in Leipzig. During that time he wrote several symphonies, church cantatas, and arias, as well as a fragmentary Singspiel entitled Das Orackle. Hiller also published an essay on the Mimesis of Nature in Music (Abhandlung über die Nachahmung der Natur in der Musik) in 1754. That year he got his first break when he became steward and tutor to the son of Count Brühl in Dresden. He accompanied the Count to Leipzig in 1758. He remained in that position until 1760 when health problems (depression) forced him to resign. It was during his stay there that he conceived the idea of reviving some subscription concerts, an attempt which ultimately led to the founding of the Leipzig Gewandhaus concerts of which he was the first conductor.