Hedvig Wilhelmina Augusta Sofia Maria Teresia Lovisa von Fersen (18 March 1816, in Stockholm – 29 December 1879, in Stockholm) was a Swedish countess and heiress, and the last member of the von Fersen family.
She was one of the greatest heirs of 19th-century Sweden and became notorious for the scandal of her and her husband's great bankruptcy, having wasted a fortune of about eight million riksdaler on an expensive lifestyle and gambling.
While Louise von Fersen had three older brothers, all died officially childless.
In 1867, they were finally declared bankrupt and their property, including Ljung and Steninge, was sold at public auction, which was a major scandal in contemporary Sweden.
Louise von Fersen reportedly smashed a set of Manufacture nationale de Sèvres given to her uncle Axel von Fersen the Younger by Louis XVI of France to prevent it from being auctioned, and was threatened with imprisonment.