Otto, Duke of Brunswick

Otto IV
Golden bull of Otto IV (1210)
Holy Roman Emperor
Reign	1209–1215
Coronation	21 October 1209, Rome
Predecessor	Henry VI
Successor	Frederick II
King of the Romans
Reign	1198–1209
Coronation	12 July 1198, Aachen
Predecessor	Henry VI
Successor	Frederick II
King of Italy
Reign	1208–1212
Predecessor	Henry VI
Successor	Henry VII
King of Burgundy
Reign	1208–1215
Predecessor	Philip of Swabia
Successor	Frederick II
Born	1175 possibly Braunschweig
Died	19 May 1218 (aged 43) Harzburg
Burial	Brunswick Cathedral
Spouse	Beatrice of Hohenstaufen Marie of Brabant
House	House of Welf
Father	Henry the Lion
Mother	Matilda of England
Religion	Roman Catholicism

Otto IV (1175 – 19 May 1218) was one of two rival kings of Germany from 1198 on, sole king from 1208 on, 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 the third son of Henry the Lion, Duke of Bavaria and Saxony, and Matilda of England. His exact birthplace is not given by any original source. He grew up in England in the care of his grandfather King Henry II. Otto was fluent in French as well as German. He became the foster son of his maternal uncle, Richard I of England. In 1190, after he left England to join the Third Crusade, Richard appointed Otto Earl of York. The authenticity (or authority) of this grant was doubted by the vassals of Yorkshire, who prevented Otto taking possession of his earldom. Still, he probably visited Yorkshire in 1191, and he continued to claim the revenues of the earldom after becoming king of Germany, although he never secured them. Neither did he succeed in getting the 25,000 silver marks willed to him by his uncle in 1199.

In 1195, Richard began negotiations to marry Otto to Margaret, daughter and heir presumptive of King William the Lion of Scotland.Lothian, as Margaret's dowry, would be handed over to Richard for safekeeping and the counties of Northumberland and Cumberland (Carlisle) would be granted to Otto and turned over to the king of Scotland. The negotiations dragged on until August 1198, when the birth of a son to William rendered them unnecessary. Having failed in his efforts to secure Otto an English earldom or else a Scottish kingdom, in September 1196 Richard, as duke of Aquitaine, enfeoffed Otto with the county of Poitou. There is some disagreement over whether Otto received Poitou in exchange for or in addition to the earldom of York.