Verdugo is the Spanish word for "Executioner" and the creatures themselves displayed characteristics of an executioner or grim
Reaper with their mask-like face and scythe-like barbed tail. At least two of them also wore a long dark cloak as an outfit giving them a mysterious look fit for a cult such as the
Los Illuminados.
They were created as an experiment into incorporating insect DNA into human subjects which had already been infected with a Plagas parasite, a unique kind of organism which could alter physical and mental traits of virtually any living thing.
Ramon Salazar, a high ranking member of the cult and the general community used the beasts as his personal bodyguards, as they had much higher intelligence than previous creatures that had been designed. As such they had the ability to obey commands, execute mission objectives given to them, handle objects and conduct itself calmly in a few basic social norms.
They tended to wear their cloaks to hide their monstrous faces and heavily mutated bodies. In this form they appeared as large human beings. Once these cloaks were discarded however, the full extent of their mutations were revealed - muscled, armoured humanoid bodies with large claws for hands and feet, an extremely long barbed tail and a face with glowing eyes and mandibles around the mouth.
Only two have ever been observed in existence by
Leon S. Kennedy. Both were defeated by him in combat - they were extremely fast and durable but had a weakness to both the extreme cold and to explosives. One of them was defeated by itself, the other one was defeated when it fused with Queen
Plaga and
Ramon Salazar into one large gestalt entity - once that form was destroyed, all three perished.
Interestingly, in
Resident Evil 4 it is possible to avoid killing one of the Verdugo, leaving it alive. It's likely that this is not a canon scenario.
Finally, the design of the Verdugo clearly resembles the titular Alien Xenomorph from the movie franchise Alien.