Iron Maiden

Iron Maidens are apparent Regenerator variants/prototypes; large humanoid creatures well above a normal human's height. They share most physical traits with the Regenerator but with slight differences; they have a larger mouth that takes up almost their whole face,have a purple hue to their skin and many large pointed spikes and nails protruding from their bodies. Their name comes from the ancient torturing tool, the Iron Maiden, which was a standing coffin of sorts filled with sharp spikes on the inside which you would lock victims into.

Much like the Regenerators, they can be shot several times with no effect and their lost limbs will regrow in a matter of seconds, even the head, and they house several leech-like Plagas as well. However, the Iron Maidens lack visible eyes and have a slower walking speed than Regenerators but can crawl much faster. The Iron Maidens tend to use their spikes as weapons, having a special attack where they grab Leon, pull him toward itself and then extend their spikes, impaling him for massive damage. They do not use their mouths to attack due to it being severely deformed (it has a mouth similar to the Gravedigger). They walk in a slow, deliberate manner, constantly suffering from rapid, spastic movements. When dying, their upper torso erratically shaby the bursting spikes from the Iron Maiden during the death sequence.

Role in Resident Evil 4
The Iron Maidens fill the basically same role as the Regenerator although they are encountered much more rarely; they are so rare, in fact, that only three iron maidens are encountered in the entire game.

Leon first encounters an Iron Maiden shortly after entering a research lab on the island when you see the beast lurking into a door through the cameras. The first Iron Maiden holds a keycard necessary to open Ashley's cell, possibly placed there to deter Leon's progress. The last is encountered in a garbage disposal area. This may seem to be more challenging than the earlier, due to Ashley's presence, but Ashley is able to hide in Dumpsters before fighting it, and Leon has the advantage of being able to close gates down on the Iron Maiden, stalling it's advance.

Due to their lack of mandible usage, the Iron Maidens lack perhaps the Regenerator's strongest and most lethal attack, the shoulder-bite. The Iron Maiden will instead try to grab, then impale you. The deadly "jumping bite" that the Regenerators use to excellent effect is replaced with the Iron Maiden repelling it's spikes, which deal medium damage and can easily be killed with the infra-red scope or a normal weapon. Just aim at the torso and shoot the places where the Plagas are.

Strategy
Despite its enhanced nature, Iron Maidens should be engaged using the same methods as a standard Regenerator, albeit with a greater caution as the distance between Leon and the Iron Maiden closes.

Trivia

 * The Iron Maiden and the regenerator have been consistently rated by video game websites to be one of the scariest creatures in Resident Evil 4.
 * Despite being stronger than their Regenerator counterparts, Iron Maidens have about the same amount of health when you kill them without using the rifle, magnum, or other penetrating weapon to attack the Plagas directly.
 * An Iron Maiden is a torture device used during the Dark ages, designed as an iron or wooden coffin tall enough to enclose a person, often with strategically placed spikes that does not pierce any vital organs or arteries, this is to give prisoners or interrogated suspects a scary and slow but painful death via bleeding or asphyxiation. Interestingly enough if an Iron Maiden grabs Leon at full health and expands his spikes on him, it does not instantly kill him rather put him in a near death state.
 * Iron Maiden is also the name of a famous British Heavy Metal band.
 * Iron maidens and regenerators can be destroyed easily with a single hit of the rocket launcher