Heinrich IX. der Schwarze Welf von Bayern, Duke of Bavaria, was born 1075 to Welf IV. von Bayern (c1035-1101) and Judith of Flanders (1033-1094) and died 13 December 1126 of unspecified causes. He married Wulfhild von Sachsen (c1075-1126) . Charlemagne (747-814), Alfred the Great (849-899)/s, Charlemagne (747-814)/s, Rollo of Normandy (860-932)/s.
Henry was the second son of Welf I, Duke of Bavaria and Judith of Flanders. As a young man, he administered the family's property south of the Alps. Through his marriage to Wulfhild, daughter of Magnus, Duke of Saxony, he acquired part of the Billung property in Saxony.
In 1116, he joined Emperor Henry V's Italian campaign. He succeeded his brother Welf II, Duke of Bavaria, when the latter died childless in 1120.