The Royal Northumberland Fusiliers was an infantry regiment of the British Army. Originally raised in 1674 as the 5th Regiment of Foot, it was given the regional designation 'Northumberland' in 1782 and granted the distinction of being a Fusilier regiment in 1836, becoming 5th (Northumberland Fusiliers) Regiment of Foot. The regiment adopted the title Northumberland Fusiliers when regimental numbers were abolished under the Childers Reforms of 1881 and became the Royal Northumberland Fusiliers on 3 June 1935.
In 1968, the Royal Northumberland Fusiliers were amalgamated with the other regiments in the Fusilier Brigade–the Royal Fusiliers (City of London Regiment), the Royal Warwickshire Fusiliers and the Lancashire Fusiliers–to form the present Royal Regiment of Fusiliers.