August Wilhelm Dennstedt (1776–1826), surname sometimes spelled Dennstaedt, was a German medical doctor and botanist who was bürgermeister of Magdala, a town near Weimar. From 1817 he was scientific director of the Grand Ducal Garden in Belvedere.
He was the taxonomic author of numerous botanical taxa; three examples being the genera Bruxanelia, Coulejia and Merremia. He entered many of his taxonomic findings in the register "Schlüssel zum Hortus indicus malabaricus". The genus Dennstaedtia <small>Bernh.</small> (family Dennstaedtiaceae) is named in his honor.