Louis Charles, Duke of Schleswig-Holstein-Sonderburg-Franzhagen (4 June 1684 – 11 October 1707) was a German nobleman and ruler from the House of Schleswig-Holstein-Sonderburg, cadet line of the House of Oldenburg.
He was the second son of Duke Christian Adolph of Schleswig-Holstein-Sonderburg-Franzhagen and his wife, Duchess Eleonore Charlotte of Saxe-Lauenburg.
In 1707, he succeeded his elder brother Leopold Christian as Duke of Schleswig-Holstein-Sonderburg-Franzhagen.
In 1705, he was married to Anna Barbara Dorothea von Winterfeld (1670-1739) in Ottensen, near Hamburg.
Although she belonged to lower nobility, their marriage was recognized as equal and their children thus had succession rights and were able to inherit the Duchy.