Which noble dynasty of Austrian margraves and dukes was Henry I a member of? 
Henry I, Margrave of Austria: Henry I (German: "Heinrich" , died 23 June 1018), known as Henry the Strong (German: "Heinrich der Starke" ), was the Margrave of Austria from 994 to his death in 1018. House of Babenberg: The House of Babenberg was a noble dynasty of Austrian margraves and dukes.
i don't know