Felix Lloyd Powell (23 May 1878 – 10 February 1942) was a Welsh British Army Staff Sergeant most famous for writing the music for marching song "Pack Up Your Troubles in Your Old Kit Bag and Smile, Smile, Smile", in 1915, during World War I. The words were written by his brother George Henry Powell (under the pseudonym George Asaf), and the song was entered into a competition for "best morale-building song". It won first prize and was noted as "perhaps the most optimistic song ever written".