Complex sentence: Brun or Bruno I, Archbishop of Cologne from 953 until his death in 965 and Duke of Lotharingia from 954, was the brother of Otto I, king of Germany and later Holy Roman Emperor.
Split into simpler sentences: Brun or Bruno I (925-965) was Archbishop of Cologne from 953 until his death, and Duke of Lotharingia from 954. He was the brother of Otto I, king of Germany and later Holy Roman Emperor.