Otto IV was king of Germany and Holy Roman Emperor from 1209 until he was forced to abdicate in 1215. The only German king of the Welf dynasty, he incurred the wrath of Pope Innocent III and was excommunicated in 1210.
Otto was a son of Henry the Lion of Brunswick and Matilda, daughter of Henry II of England. He grew up in England in the care of his grandfather. Otto was fluent in French as well as German. Otto 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 nothing came of this decree until Otto decisively lost the battle of Bouvines (July 1214) to the forces of Philip II of France. He was deposed in 1215 and died on 19th May 1218.
Depicted here is 1 Grosso issued under his reign. The obverse depicts the Large H in circle +OTTO REX around. The reverse of a coin shows the head of Christ.
Image Source: https://www.cngcoins.com/