John III, Duke of Saxe-Lauenburg
John III of Saxe-Lauenburg was the eldest son of Duke Albert IV of Saxe-Lauenburg and Beata of Schwerin, daughter of Gunzelin VI, Count of Schwerin. John III succeeded his father in 1343 as Duke of Saxe-Bergedorf-Mölln, a branch duchy of Saxe-Lauenburg. He died without an heir and was succeeded by his younger brother Albert V.