Thietmar (I) (also Thiatmar, Dietmar, or Thiommar) (died 1 June 932), Count and Margrave, was the military tutor (vir disciplinae militaris peritissmus) of Henry the Fowler while he was the heir and then duke of the Duchy of Saxony. He probably kept a small body of elite retainers (though he once feigned at having thirty legions behind him) armed with the latest in military technology and well-supplied with expensive horses.