Charles of Blois was a French nobleman born in 1319, known for his role in the Brittany War of Succession. He was the son of Guy of Blois and became the Duke of Brittany through his marriage to Joanna of Penthièvre, who claimed the duchy. Charles was a key figure in the conflict between the houses of Blois and Montfort over the control of Brittany. His efforts to secure the duchy led to a series of battles, but he was ultimately captured and killed in 1364, marking a significant moment in Breton history.