Nicolaus Thomas Host (December 6, 1761 in Fiume, now Rijeka – January 13, 1834 in Schönbrunn) was an Austrian botanist, and the personal physician of Holy Roman Emperor Francis II. His botanical works include Synopsis plantarum in Austria and the four-volume Austriacorum Icones et descriptions graminum; he was also the first director of the botanical garden at the Belvedere palace. The genus Hosta is named for him.