Otto IV of Brunswick (died 1218) was King of Germany (1208-1215) and Holy Roman Emperor from 1209 - 1215.
He was the son of Henry the Lion, Duke of Bavaria and Saxony and Matilda Plantagenet, and was elected king when his rival for the throne, Philip of Swabia (Hohenstaufen), was murdered. Otto had been supported by Pope Innocent III, but Innocent withdrew his support after Otto's military adventures in Italy. In 1211 the Diet of Nuremberg ordered Otto deposed and Frederick II Hohenstaufen elected in his place, but until Otto lost the battle of Bouvines (July, 1214) decisively to the forces of Philip II of France nothing happened. He was deposed in 1215 and died in 1218.
