Geoffrey I, Duke of Brittany was a nobleman who lived during the 11th century. He was born around 1000 and became the Duke of Brittany in 1040. Geoffrey was the son of Conan I, Duke of Brittany and Ermengarde of Anjou, and he played a significant role in the political landscape of medieval France. Geoffrey I is known for his efforts to strengthen the duchy and maintain its independence from the influence of the French crown. He ruled until his death in 1072, after which his son, Hoel I, Duke of Brittany, succeeded him. Geoffrey's legacy contributed to the ongoing development of Brittany as a distinct region.