Otto I, Duke of Brunswick-Lüneburg

Otto I, called the Child (c. 1204–1252), was the only son of William of Winchester and Helena, daughter of King Valdemar I of Denmark. He inherited the Welf estates around Lüneburg as a minor in 1213. When Emperor Frederick II tried to seize Brunswick after his uncle's death, Otto, backed by the town and the estates, drove the imperial forces out.

In 1235 Frederick enfeoffed him as first duke of Brunswick-Lüneburg. He died in 1252 and was buried in Brunswick Cathedral.