Johann Gottlieb Stephanie the Younger (19 February 1741 – 23 January 1800) was an Austrian playwright, director and librettist, most famously to Mozart.

Stephanie was born in Breslau, Prussia, but came to Vienna during the Seven Years' War as a Prussian prisoner of war. He was appointed to head the National Singspiel, a favourite project of Emperor Joseph II. He died in Vienna, aged 58.

Stephanie's adaptation of Christoph Friedrich Bretzner's Entführung has been harshly criticized; E. J. Dent called it "the very worst that he ever set to music." Mozart wrote to his father saying that "you are quite right so far as Stephanie's work is concerned. ... I am well aware that the verse is not of the best."

In 1769 Stephanie adapted Shakespeare's Macbeth to suit popular taste in Vienna. It was performed in the 1770s.