Charles Louis, Duke of Schleswig-Holstein-Sonderburg-Beck (German: Karl Ludwig Herzog von Schleswig-Holstein-Sonderburg-Beck; 18 September 1690 – 22 September 1774) was a Lieutenant General in the Prussian Army and Governor of Reval (Tallinn) in the Governorate of Estonia.

Charles Louis became the titular Duke of Schleswig-Holstein-Sonderburg-Beck in 1757 after his nephew Colonel Frederick William III died in the Battle of Prague without leaving a male heir.

He was appointed field marshal by Czar Peter III of Russia in 1762, but he refused because of his age.

In 1730 he married Countess Anna Karolina Orzelska in Dresden, Electorate of Saxony.

She was an illegitimate daughter of August II the Strong, Prince-Elector of Saxony and King of Poland and Grand-Duke of Lithuania, by his French mistress Henriette Rénard.