Johanna Magdalene of Saxe-Weissenfels (17 March 1708 â 25 January 1760), was a Duchess consort of Courland and by marriage member of the House of Kettler. By birth she was member of the Saxe-Weissenfels line of the House of Wettin.
She was the born as only surviving daughter of Johann Georg, Duke of Saxe-Weissenfels and his wife, Princess Fredericka Elisabeth of Saxe-Eisenach.
On 20 September 1730, in Danzig, she married Ferdinand Kettler, the Duke of Courland, who was 75 years old at the time. The marriage remained childless.