The Lancashire Fusiliers was a British infantry regiment that was amalgamated with other Fusilier regiments in 1968 to form the Royal Regiment of Fusiliers.

Originally raised in Devonshire, the regiment was named Sir Richard Peyton's Regiment of Foot in 1688. The regiment's name changed according to the name of the colonel commanding until in 1751 it became the 20th Regiment of Foot. The regiment became the county regiment of Lancashire in 1881 and was renamed the Lancashire Fusiliers.

During Battle of France of World War II, the 1/8 Battalion, Lancashire Fusiliers, along with battalions of the Royal Norfolks and the Royal Scots, were overrun on 26-27 May 1940 around the village of Locon, 2 kilometres north of Bethune. The SS Totenkopf Division were mainly responsible for the massacres of prisoners which took place over the next couple of days.

The famous fantasy author J.R.R Tolkien served in this regiment from 1915 until contracting "trench fever" during the Battle of the Somme in October 1916.