Carlo is an Italian variant of Charles. Charles originates in Germanic languages and means "free man". It has been one of the most popular masculine given names over centuries, and in different spellings all over the world. Popular with European royalty, the famous bearers include several emperors, kings, dukes and princes, currently the most famous being Charles, Prince of Wales, the eldest son of Queen Elizabeth II. Recently, the popularity of the name Charles has declined in the United States.