9) was an infantry regiment in Weimar Republic's Reichswehr and Nazi Germany's Wehrmacht, descended from famed 1st Prussian Regiment of Foot Guards in the German Empire's Deutsches Reichsheer.

Garrisoned at the cradle of Prussian army and rich with tradition, it was nicknamed 'Count Nine' (Graf Neun) or 'I.R.

von 9' by its detractors because of high percentage of Prussian aristocrats and purported arrogance in its ranks.

Most of them were executed or committed suicide after the failure of the 20 July plot to assassinate Hitler.

Major General Henning von Tresckow and Lieutenant Colonel Fritz-Dietlof von der Schulenburg in particular were central figures in German resistance.