Carolus Clusius (born February 19, 1526, Arras, France—died April 4, 1609, Leiden, Netherlands) was a botanist who contributed to the establishment of modern botany.
He was best known by the Latin version of his name, Carolus Clusius. He developed new cultivated plants, such as the tulip, potato, and chestnut, from other parts of the world. From 1573 to 1587 he was the director of the Holy Roman emperor’s garden in Vienna, and he spent the later years of his life teaching in Leiden, where his cultivation of tulips in the botanic garden was the beginning of the Dutch tulip bulb industry.