August Wilhelm Hupel (25 February 1737 Buttelstedt near Weimar – 7 February 1819 Paide; Old Style: 14 February 1737 – 26 January 1819) was a Baltic German publicist, estophile and linguist. In 1766–1767, he translated for Lühhike öppetus, the first Estonian language periodical publication, edited by Peter Ernst Wilde. In 1771, he published a medical textbook, Arsti ramat nende juhhatamisseks kes tahtvad többed ärra-arvada ning parrandada (Estonian for Manual of medical diagnostics and healthcare, literally Doctor's book to instruct those who want to guess and repair ailments).
In 1780, Hupel completed a treatise on Estonian grammar, Ehstnische Sprachlehre für beide Hauptdialekte, den revalschen und den dörptschen, nebst einem vollständigen Wörterbuch. First printing of the included dictionary contained around 17,000 words and description of their morphology. The second printing, printed in 1820, had grown to around 20,000 words.