El Gigante (literally "The Giant" in Spanish) is the name given to the human Plaga hosts who have mutated to extraordinary size. They have great strength and brutality to compensate for their loss of higher reasoning.
El Gigante was created by Los Iluminados as one of their experiments on Plaga hosts. Due to their limited intelligence and feral nature, only a few were created, who were then imprisoned underground. In Autumn 2004, when Leon S. Kennedy ventured through Spain, one of them was deployed into the area behind the church to stop him. Trapping Leon in a small, fenced area, the creature was released from the mine in which it was incarcerated. Unfortunately for his Ganado handlers, he proved to be uncontrollable and succeeded in killing them all before turning to Leon.
A second El Gigante was deployed, again via the mines, to stop Leon and Ashley's escape; Ada also encounters this El Gigante on her way to rendezvous with Luis. Another two were encountered by Leon in the mines beneath the castle.