Albrecht, Duke of Saxe-Eisenach, (b. Altenburg, 27 July 1599 - d. Eisenach, 20 December 1644) was a ruler of the duchy of Saxe-Eisenach. He was the seventh (but fourth surviving) son of Johann, Duke of Saxe-Weimar, and Dorothea Maria of Anhalt. His regnal name Albert IV derives from the numbering of the duchy of Saxony as a whole, not specifically to the succession in Saxe-Eisenach.