Duchess Dorothea Sophia of Saxe-Altenburg (19 December 1587 – 10 February 1645) was Princess-Abbess of Quedlinburg.
She was the fourth child and second daughter of Friedrich Wilhelm I, Duke of Saxe-Weimar, and his first wife, Sophie of Württemberg.
On 21 April 1618, Dorothea Sophia was elected successor to Princess-Abbess Dorothea. Her election was approved by Matthias, Holy Roman Emperor.
During her reign, Quedlinburg was devastated by the Thirty Years' War. Unlike her predecessors, Princess-Abbess Dorothea Sophia often confronted John George I, Elector of Saxony.
Dorothea Sophia prohibited her clergy to deny absolution to a person who made a genuine and contrite confession. However, if the same parishioner repeated the sin, they were to face increasingly severe chastisement and, finally, a referral to the consistory. She proscribed that these parishioners would not be able to serve as godparents, nor be buried according to tradition or within consecrated ground. These decisions were a lot like the previous Catholic practice. She also took measures to prevent secret engagements, declaring that every engagement has to be witnessed by three men and publicly announced.