Louise Isabelle Alexandrine Auguste, Countess of Sayn-Hachenburg, Burgravine of Kirchberg, full German name: Luise Isabelle Alexandrine Auguste, Gräfin zu Sayn-Hachenburg, Burggräfin von Kirchberg (19 April 1772, Hachenburg – 6 January 1827, Vienna, Austrian Empire) was the Princess consort of Nassau-Weilburg (28 November 1788 – 9 January 1816) through her marriage to Frederick William, Prince of Nassau-Weilburg.