Pfalzgraf
Duke Otto I was probably born at Kelheim, the son of Count Palatine Otto IV of Wittelsbach and Heilika of Pettendorf-Lengenfeld, a granddaughter of the Hohenstaufen duke Frederick I of Swabia. He was the brother of Archbishop Conrad I of Mainz and Salzburg. Upon the death of his father in 1156, he succeeded him as Count palatine of the Bavarian duchy, then under the rule of Henry the Lion, a scion of the Welf dynasty.