The 1st Foot Guard Regiment was an infantry regiment of the Royal Prussian Army formed in 1806 after Napoleon defeated Prussia in the Battle of Jena–Auerstedt. It was formed by combining all previous Foot Guard Regiments, especially the 6th and the 15th Infantry Regiments of the Old Prussian Army, the former were the famous Potsdam Giants of Frederick William I of Prussia, the latter was commanded and led by Frederick the Great as his life guard, and was, from its inception, the bodyguard-regiment of Kings of Prussia. Save William II, who also wore the uniforms of other regiments, all Prussian Kings and most Princes of Prussia wore the uniform of the 1st Foot Guard Regiment. All Princes of Prussia were commissioned lieutenants in the 1st Foot Guards upon their tenth birthdays. The King of Prussia was also the Colonel-in-chief of the regiment, as well as the Chief of the 1st Battalion and 1st Company of the regiment. Therefore, the regiment held the highest rank within the Prussian Army, which, among other things, meant that the officer corps of the regiment marched before the princes of the German Empire and the diplomatic corps in the traditional New Year's reception. Unofficially, the regiment was known as the "First Regiment of Christendom".

The Potsdam Giants was the name given to Prussian infantry regiment No 6. The regiment was composed of taller-than-average soldiers, and was founded in 1675. It was eventually dissolved in 1806, after the Prussians were defeated by Napoleon. Throughout the reign of the Prussian king Friedrich Wilhelm I of Prussia (1688–1740), the unit was known as the "Potsdamer Riesengarde" in German, but the Prussian population quickly nicknamed them the Lange Kerls.