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.
Louis Charles was the second son of Duke Christian Adolph of Schleswig-Holstein-Sonderburg-Franzhagen and Duchess Eleonore Charlotte of Saxe-Lauenburg.
In 1707, Louis succeeded his elder brother Leopold Christian as Duke of Schleswig-Holstein-Sonderburg-Franzhagen. However, he died later that year.
In 1705, Louis married Anna Barbara Dorothea (1670-1739) in Ottensen, near Hamburg. She was the daughter of Barthold Dietrich and Sophie Margarete . 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. They had:
His son Christian succeeded as Christian II Adolph, Duke of Schleswig-Holstein-Sonderburg-Franzhagen. As he was still a minor, he reigned under the regency. With his death in 1709, the Schleswig-Holstein-Sonderburg-Franzhagen line died out.