Anthonius Josephus Maria "Toon" Leeuwenberg (11 August 1930, in Amsterdam – 2010) was a Dutch botanist and taxonomist best known for his research into the genus Buddleja at the Laboratory of Plant Taxonomy and Plant Geography, Wageningen. He was responsible for sinking many Asiatic species as varieties, notably within Buddleja crispa. In 1962, he worked with on the flora of the Ivory Coast.