Francis I, duke of Saxe-Lauenburg (b. 1510)
Francis I of Saxe-Lauenburg (1510 – 19 March 1581, Buxtehude) was the eldest child and only son of Duke Magnus I of Saxe-Lauenburg and Catherine of Brunswick-Wolfenbüttel (1488 – 29 July 1563, Neuhaus), daughter of Duke Henry IV the Evil of Brunswick and Lunenburg (Wolfenbüttel). Francis I succeeded his father in 1543 as duke of Saxe-Lauenburg, but resigned in favour of his major son Magnus II in 1571. Two years later he reascended and was succeeded by Francis II in 1581.