In Europe

• The Imperial Army
  Imperial Army of the Holy Roman Empire
  The Imperial Army of the Holy Roman Empire was the army of the Holy Roman Empire...
  
   of the Holy Roman Empire
  Holy Roman Empire
  The Holy Roman Empire was a realm that existed from 962 to 1806 in Central Europe.It was ruled by the Holy Roman Emperor. Its character changed during the Middle Ages and the Early Modern period, when the power of the emperor gradually weakened in favour of the princes...
  
   (until 1806)
• The Imperial German Army
  German Army (German Empire)
  The German Army was the name given the combined land forces of the German Empire, also known as the National Army , Imperial Army or Imperial German Army. The term "Deutsches Heer" is also used for the modern German Army, the land component of the German Bundeswehr...
  
   (1871-1918)
• the Austro-Hungarian Army
  Austro-Hungarian Army
  The Austro-Hungarian Army was the ground force of the Austro-Hungarian Dual Monarchy from 1867 to 1918. It was composed of three parts: the joint army , the Austrian Landwehr , and the Hungarian Honvédség .In the wake of fighting between the...
  
   (1804-1918)
• Armies of the Russian Czars and the French Emperor, e.g. in the Battle of the three emperors at Austerlitz

Elsewhere

• The Imperial Japanese Army
  Imperial Japanese Army
  -Foundation:During the Meiji Restoration, the military forces loyal to the Emperor were samurai drawn primarily from the loyalist feudal domains of Satsuma and Chōshū...
  
  
• The Imperial Chinese Army
  Imperial Chinese Army
  Imperial Chinese Army was the ground force of the military of Imperial China.The army varied in size over the years and weakened towards the end of the Imperial rule over China.-Weapons:* Chariots* Bow or crossbow - Shang Dynasty* Swords* Spears...
  
  
• The Manchukuo Imperial Army
  Manchukuo Imperial Army
  The Manchukuo Imperial Army was the armed force of the Japanese dominated puppet state of Manchukuo, serving as the land forces, along with the Manchukuo Imperial Guards...
  
  
• The Imperial Iranian Army

Fictional

• The Imperial Army (Star Wars) of the fictional Galactic Empire in Star Wars
• The Imperial Army of the Archadian Empire in the video game Final Fantasy XII
  Final Fantasy XII
  is a console role-playing video game developed and published by Square Enix for the PlayStation 2. Released in 2006, it is the twelfth title in the Final Fantasy series and the last in the series to be released exclusively on the PlayStation platform...
  
  
• The Imperial Army of the Imperium of Man in Warhammer 40000