Caroline Frederikke Müller (née Halle; 5 February 1755 – 17 November 1826), also known as Caroline Walther, was a Danish and later naturalized Swedish singer (mezzo-soprano), dancer and actor and principal of the theatre academy Dramatens elevskola. She was born as Caroline Halle, was known in Denmark as Caroline Walther (after her first marriage in 1774), and in Sweden as Caroline Müller (after her second marriage in 1780). She was a member of the Royal Swedish Academy of Music and a royal court singer (Hovsångare).
Born an illegitimate child, her stepfather Thomas Jespersen, who was employed as a machinist at the Royal Danish Theatre, got her accepted as a student there. At the age of six, she danced at the Royal Danish Theatre ballet; she debuted as an actress in 1768, and in 1769, she was employed as a singer and actress and became one of the most celebrated stage artists in Denmark.
During the 1770s, she was considered to be one of the greatest talents within Danish opera. In 1772, she played 124 parts, in everything from romantic drama to tragedy; she followed in the footsteps of her mentor, the versatile primadonna Lisbeth Cathrine Amalie Rose. In 1773, she left her mother, who had abused her, and, in 1774, she married the music instructor and secretary Thomas Walther; however, they separated in 1775 when he moved abroad.
In 1780, she herself left Denmark, and moved to Sweden; she wished to gain a divorce so that she could remarry, but had not been permitted to by the authorities in Denmark - this is reported to be as a result of an intrigue planned by her great rival, Catharine Frydendahl. In 1777, General von Eickstedt became a part of the management of the opera, and it is said that he worked to benefit the career of his mistress Frydendahl. He prevented that Caroline Frederikke Müller's lover became employed at the opera, and had him exiled. The opera direction was reportedly afraid that they would lose Caroline if she married a foreigner.