A Regenerator is a enemy from the Resident Evil series of survival horror games.
It is a mutated humanoid from the game Resident Evil 4, created from experiments with Las Plagas and human specimens. According to the notes of Luis Sera, they are the most "clearly distinguishable" creatures born from Osmund Saddler's experiments.
As the name suggest, they can regenerate lost body parts in a matter of seconds, and are extremely resistant to direct damage, but are unable to live without the leech-shaped Plagas which inhabit them, which are only visible using thermal imaging equipment. When a Regenerator has lost all inhabiting Plagas, its tissue will begin to expand rapidly and explode, leaving only its legs.
Regenerators can stretch their limbs to reach opponents, pull them in, and bite them with their sharp teeth. They also demonstrate the ability to slither on the ground at impressive speeds after one of their legs has been shot off, and their slithering movement is in fact faster than their normal walking. They can also leap from a prone position. The Regenerator can range from having two to five parasites, depending on difficulty level and location encountered.
In Professional Mode, all Regenerators have a fifth parasite on their back.