Magdalena Sibylla of Neidschutz (8 February 1675 – 14 April 1694), later Countess of Rochlitz, was a German

Germans

The Germans are a Germanic ethnic group native to Central Europe. The English term Germans has referred to the German-speaking population of the Holy Roman Empire since the Late Middle Ages....

 noblewoman and the mistress

Mistress (lover)

A mistress is a long-term female lover and companion who is not married to her partner; the term is used especially when her partner is married. The relationship generally is stable and at least semi-permanent; however, the couple does not live together openly. Also the relationship is usually,...

 of John George IV

John George IV, Elector of Saxony

John George IV was Elector of Saxony from 1691 to 1694.He was the eldest son of the Elector John George III and Anna Sophie of Denmark.-First years as elector:...

, Elector of Saxony. She was the first ever Official Mistress (Favoritin) of an Elector of Saxony.

Magdalena Sibylla, called "Billa", was the daughter of Ursula Margarethe of Haugwitz, who had at one time been the mistress of Elector Johann Georg III

John George III, Elector of Saxony

Johann Georg III was Elector of Saxony from 1680 to 1691.-Early life:Johann Georg was the only son of the Elector Johann Georg II and Magdalene Sybille of Brandenburg-Bayreuth....

. By order of the Elector, Ursula married Colonel Rudolf of Neidschutz, who officially appears as the father of Billa, though there were rumors that Billa was in fact the child of Johann Georg. If this had been true, it would have made Billa half-sister of her lover, John Georg IV.

Billa became mistress of John George IV in late 1691. By order of his mother, he was forced to marry, in April 1692, in an attempt to break up the affair. Instead, immediately after he assumed the Electorate, he openly lived with Billa, and she became the first ever Official Mistress (Favoritin) of an Elector of Saxony. John George abandoned his wife in the official residence and moved into another palace with Billa.

On 20 February 1693, Leopold I

Leopold I, Holy Roman Emperor

| style="float:right;" | Leopold I was a Holy Roman Emperor, King of Hungary and King of Bohemia. A member of the Habsburg family, he was the second son of Emperor Ferdinand III and his first wife, Maria Anna of Spain. His maternal grandparents were Philip III of Spain and Margaret of Austria...

 gave her the title Reichsgräfin von Rochlitz.

She had an illegitimate daughter with John George IV:

• Frederica of Rochlitz (summer
  Summer
  Summer is the warmest of the four temperate seasons, between spring and autumn. At the summer solstice, the days are longest and the nights are shortest, with day-length decreasing as the season progresses after the solstice...
  
   1693 – after 1729): wife of Count Piotr Dunin.

She died in Dresden

Dresden

Dresden is the capital city of the Free State of Saxony in Germany. It is situated in a valley on the River Elbe, near the Czech border. The Dresden conurbation is part of the Saxon Triangle metropolitan area....

 of smallpox

Smallpox

Smallpox was an infectious disease unique to humans, caused by either of two virus variants, Variola major and Variola minor. The disease is also known by the Latin names Variola or Variola vera, which is a derivative of the Latin varius, meaning "spotted", or varus, meaning "pimple"...

, in the arms of John George IV, who himself became infected with the disease and died 23 days later.