Mariane Theresia Sophie Stebnowska (or Maria Sofia Stempkosta; 1753 – 16 February 1848), was a Polish opera singer, actor and harpist. She was among the great talents of the Royal Swedish Opera in during the reign of King Gustav III of Sweden. She was married to the opera singer Christoffer Christian Karsten and was also the maternal grandmother of the world-famous ballet dancer Marie Taglioni.
Sophie Stebnowska, noted as "an excellent harp player", arrived in Sweden from Paris in the company of the British ambassador to Sweden, Sir Thomas Wroughton, with whom she was in a relationship at the time.
She was married in 1781 to the Swedish opera singer Christoffer Christian Karsten. In December 1782, she was appointed premier actress and singer of the Royal Swedish Opera in , a position she kept for 21 years. At the wedding, the couple were given the villa Canton at Drottningholm. Though she did not reach the rank of prima donna, she was considered among the opera's most valuable members, just behind the prima donnas Elisabeth Olin and then Caroline Frederikke Müller during the 1780s and 1790s.
She was also active as a musician. In March, 1795, she participated in a public concert in Stockholm arranged by Karsten where she played the harp, while her husband and Marie Louise Marcadet sang; first, each three of them performed in their fields by themselves, then jointly. By 1803, she was no longer premier actress, and in 1806, she and her husband left their positions after the temporary closure of the opera.
Gustav Löwenhielm mentions her importance in the 19th century, during a discussion about the employment of foreign artists, when he points out that several of the artists during the foundation of the Royal Swedish Opera and the Royal Dramatic Theatre had been foreigners: