The 100th Regiment of Foot, or the Loyal Lincolnshire Regiment, was an infantry regiment of the British Army, formed in 1780 and disbanded in 1785. The Loyal Lincolnshires were reformed in 1794 as the 123rd Regiment of Foot (Loyal Lincolnshire) and was again disbanded in 1796.
The regiment was raised in Ireland by Colonel Thomas Humberstone, with Lieutenant-General Thomas Bruce assuming the colonelcy in August 1780. It was dispatched to India shortly after being raised, and fought in the Second Anglo-Mysore War; after surrendering in May 1783, it was interned before returning to Ireland in 1784.
The "Loyal Lincolnshire" title was later reused by the 123rd Foot, raised in 1794.