The four Holy Roman Emperors were Otto I, Otto II, Otto III, and Otto IV. They were all members of the Ottonian dynasty, which was a German royal family that ruled from 919 to 1024. Otto I was crowned in 962 and is known for his successful military campaigns and for reviving the power of the Holy Roman Empire. Otto II was crowned in 967 and is known for his unsuccessful military campaigns and for his patronage of the arts. Otto III was crowned in 983 and is known for his efforts to expand the empire and for his religious reforms. Otto IV was crowned in 1209 and is known for his struggles with the papacy and for his involvement in the civil war of the Holy Roman Empire.