Francis Erdmann of Saxe-Lauenburg (Theusing, 25 February 1629 – 30 July 1666, Schwarzenbek), was duke of Saxe-Lauenburg between 1665 and 1666. He was the eldest son of Duke Julius Henry and his second wife Elisabeth Sophia of Brandenburg, daughter of John George, Elector of Brandenburg.

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In 1654 Francis Erdmann married his half-cousin Sibylle Hedwig of Saxe-Lauenburg (30 July 1625 – 1 August 1703, Ratzeburg), daughter of Duke Augustus. Since their marriage remained without heir Francis Erdmann was succeeded by his half-brother Julius Francis.