The 109th Mixed Brigade (Spanish: 109.ª Brigada Mixta), was a mixed brigade of the Spanish Republican Army in the Spanish Civil War. It was formed in the spring of 1937 in Utiel with four battalions, the 433, 434, 435 and 436.This ill-fated brigade operated mostly in Extremadura and was annihilated in the Battle of Mérida pocket in 1938. Its survivors ended up in Francoist concentration camps, where some of them would be shot.