The Loyal Lusitanian Legion (LLL) was a foreign volunteer corps of the British Army, organized with Portuguese émigrés in England, that fought in the Peninsular War.

The LLL was created by the initiative of Portuguese Army Colonels José Maria Moura[citation needed] and Carlos Frederico Lecor[citation needed] – exiled in England after the occupation of Portugal by the Napoleonic Army – and the Portuguese Ambassador in London Chevalier de Sousa, with the support of the British government.

It was present at the battles of Busaco (Portugal, 27.9.1810; ca 2,000 men; commander: Baron Eben, German,* 1773; source: O. Pusch, 1986) and Talavera de la Reina, but was especially used to conduct raids and other irregular operations in the rear of the French Army, as part of Portuguese and Spanish militia forces.

The Loyal Lusitanian Legion was organized as a regiment of light infantry, with an attached artillery battery.

As a light infantry unit, the Loyal Lusitanian Legion received green uniforms similar to those of the British rifles regiments.