Louis I of Anhalt-Köthen (German: Ludwig I., Fürst von Anhalt-Köthen; 17 June 1579 in Dessau – 7 January 1650 in Köthen), was a German prince of the House of Ascania and ruler of the unified principality of Anhalt.
From 1603, he was ruler of the principality of Anhalt-Köthen.
He was also a founder of the first German Society (the Fruitbearing Society).
Louis was the seventh son of Joachim Ernest, Prince of Anhalt, but fifth-born son of his second wife Eleonore, daughter of Christoph, Duke of Württemberg.