Lou Andreas-Salome (1861 - 1937) was a Russian-born libertine and companion to many male artists and authors of the late 19th and early 20th centuries.

Born in St. Petersburg to a Russian army general and his wife, Lou was their only daughter; she had five brothers. She sought an education beyond a typical woman's station of that time and place, so when she was seventeen Lou persuaded Dutch preacher Hendrik Gillot , twenty-five years her senior, to teach her theology, philosophy, world religions, and French and German literature. When Gillot became so smitten with Lou that he planned to divorce his wife and marry her, Lou and her mother fled to Zurich, Switzerland so she could acquire a university education. The journey was also meant to prove beneficial for Lou's physical health; she was already coughing up blood by this time.

Lou's mother took her to Rome, Italy when she was 21. At a literary salon in the city, Lou became acquainted with Paul Ree , an author and compulsive gambler whom she proposed living out of wedlock with in an academic commune. After two months, Lou persuaded him to accept her as a partner and not a wife. On May 13, 1882, Lou had also persuaded Friedrich Nietzsche, a friend of Ree's, to do the same.

The three traveled with Lou's mother through Italy and considered where they would set up their "Winterplan" commune. Arriving in Leipzig, Germany in October, Lou and Ree separated from Nietzsche as a result of the latter's unrequited love for Lou. Lou and Ree set up housekeeping in Berlin and remained together until her marriage to linguistics scholar Carl Friedrich Andreas . Despite her opposition to marriage and open collaboration with many other men, Lou and Carl remained married from 1887 until his death in 1930. They also set up housekeeping in Berlin, a situation which drove Ree out of Lou's life despite her assurances.

Throughout her married life, Lou also engaged in affairs and correspondence with French journalist George Lebedour , German poet Rainer Maria Rilke, Viktor Tausk , and Viennese psychoanalyst Sigmund Freud. Accounts of many of these are given in her volume Looking Back , and her literary and analytical studies took on such a vogue in Göttingen, the German town in which she lived her last years, that the Gestapo waited until shortly after her death by uremia in 1937 to burn her library. She is said to have remarked in her last hours of life that, when she allowed her thoughts to roam, she found no one but herself.