Otto I of Brunswick-Lüneburg, a member of the House of Welf, was the first duke of Brunswick-Lüneburg from 1235 until his death. He is called Otto the Child to distinguish him from his uncle, Emperor Otto IV. Wikipedia
Born: 1204
Died: June 9, 1252 (age 48 years), Lüneburg, Germany
Grandparents: Henry the Lion, Matilda of England, Duchess of Saxony, Valdemar I of Denmark, and more
Spouse: Matilda of Brandenburg, Duchess of Brunswick-Lüneburg (m. 1228–1252)