66th Regiment

• 66th (Berkshire) Regiment of Foot
• 66th (Leeds Rifles) (West Yorkshire Regiment) Heavy Anti-Aircraft Regiment, Royal Artillery
• 66th Armor Regiment
• 66th Armoured Regiment (India)
• 66th Division (disambiguation)
• 66th Illinois Volunteer Infantry Regiment
• 66th Indiana Infantry Regiment
• 66th Infantry Regiment (Imperial Japanese Army)
• 66th Infantry Regiment (United States)
• 66th New York Volunteer Infantry
• 66th Ohio Infantry
• 66th Punjabis
• British Army
• British Indian Army
• Imperial Japanese Army
• Indian Army
• US Army
• United States Army