John III of Saxe-Lauenburg

John III of Saxe-Lauenburg (c. 1335–1356) was the eldest son of Duke Albert IV and Beata of Schwerin. On his father's death in 1343 he succeeded as duke of the Saxe-Bergedorf-Molln branch of Saxe-Lauenburg.

In 1356 he died without an heir, and the branch duchy passed to his younger brother Albert V; a third brother, Eric III, in turn succeeded Albert later.