Alwin Berger (1871 – 20 April 1931) was a German botanist best known for his contribution to the nomenclature of succulent plants, particularly agaves and cacti. Born in Germany he worked at the botanical gardens in Dresden and Frankfurt. He was curator of the Giardini Botanici Hanbury, the garden of Sir Thomas Hanbury in La Mortola, near Ventimiglia in northwestern Italy, close to the border with France, from 1897 to 1914. After working in Germany from 1914 to 1919, he studied in the U.S. for three years, before spending his final years as director of the department of botany of the natural history museum in Stuttgart.
His main work, Die Agaven, published in 1915, described 274 species of agave, divided into 3 subgenera, Littaea, Euagave and Manfreda. He also recognised a new genus of cactus, Roseocactus, in 1925.
The genera Bergerocactus (Cactaceae) and Bergeranthus (Mesembryanthemaceae) are named in his honour.
The standard author abbreviation A.Berger is used to indicate this individual as the author when citing a botanical name.