Anna Magdalena Bach (née Wilcke; 22 September 1701 – 27 February 1760) was a German professional singer and the second wife of Johann Sebastian Bach.

Anna Magdalena Wilcke was born at Zeitz, in the Duchy of Saxe-Zeitz. While little is known about her early musical education, the family was musical. Her father, Johann Caspar Wilcke (c. 1660–1733), was a trumpet player, who had a career at the courts of Zeitz and Weißenfels. Her mother, Margaretha Elisabeth Liebe, was the daughter of an organist.

By 1721, Anna Magdalena was employed as a soprano singer at the princely court of Anhalt-Cöthen. Johann Sebastian Bach had been working there as Capellmeister (director of music) since December 1717. Johann Sebastian, 36, married the 20-year-old Anna Magdalena on 3 December of that year, seventeen months after the death of his first wife, Maria Barbara Bach. Later that month, the couple's employer, Prince Leopold of Anhalt-Cöthen, married Frederica Henriette of Anhalt-Bernburg. Bach believed the princess' lack of interest in music caused the musical life at the court to decline, although there is evidence that other factors were involved. There were budgetary constraints of which Bach may have had limited knowledge, as it is unlikely that the prince would have discussed his financial problems with Bach. In May 1723, the Bachs moved to Leipzig, where Johann Sebastian had been appointed Cantor of the Thomasschule and music director of the town.

Anna Magdalena continued to sing professionally after her marriage. In one notable example of her continuing involvement with music, she returned to Köthen in 1729 to sing at Prince Leopold's funeral.

Her husband brought four children into the marriage. Between 1723 and 1742, she gave birth to the following children: Christiana Sophia Henrietta (⁕spring 1723 †29 June 1726); Gottfried Heinrich (⁕26 February 1724 ⚰12 February 1763); Christian Gottlieb (〰14 April 1725 †21 September 1728); Elisabeth Juliana Friderica, called "Liesgen", who married Bach's pupil Johann Christoph Altnickol (〰5 April 1726 †24 August 1781); Ernestus Andreas (〰30 October 1727 †1 November 1727); Regina Johanna (〰10 October 1728 †25 April 1733); Christiana Benedicta (〰1 January 1730 †4 January 1730); Christiana Dorothea (〰18 March 1731 †31 August 1732); Johann Christoph Friedrich, called "Friedrich", the 'Bückeburg' Bach (⁕21 June 1732 †26 January 1795); Johann August Abraham (〰5 November 1733 †6 November 1733); Johann Christian, called "Christel", the 'London' Bach (⁕5 September 1735 – †1 January 1782); Johanna Carolina (〰30 October 1737 †18 August 1781) and Regina Susanna (〰22 February 1742 †14 December 1809)

As can be seen from the dates, seven of her 13 children died before reaching adulthood. Only during the ten weeks from June to August 1732 were five of the couple’s children younger than 10 years of age living in the household. Otherwise, there were four or less. Anna Magdalena was seriously ill seven months before the birth of her last daughter Regina Susanna, and it is not known whether this was related to the pregnancy.

With the marriage Anna Magdalena became Frau Capellmeisterin Bach, because she had the right to bear the title of her husband. It was not the job of a lady of her standing to cook, clean the apartment or do the washing. There were service personnel for this. Infants were nourished by wet nurses. Together with her husband, Anna Magdalena Bach commanded a household to which not only the children belonged, but also private students and servants. In this household the livelihood was earned through music. As a musician herself and the daughter of a court trumpeter, Anna Magdalena had the abilities and experience to monitor and participate in the activities. In the Bach family household works composed by Johann Sebastian were copied and prepared for performance. Performances were rehearsed, music was traded, private students taught, instruments rented out and sold. Anna Magdalena cooperated in all these areas. When her husband was away examining organs or for other reasons, she was responsible for running the business. The entire household could also have been organised such that she could accompany him. After the death of her husband a cantata for the council election was commissioned from her – proof that she was capable of organising such a performance. Several copies of her husband’s compositions made by her have survived. Some of these are of high musicological significance as many of his own manuscripts are lost. Apart from music, Anna Magdalena was interested in flowers.

Johann Sebastian Bach died on 28 July 1750.