Grevac

Grevac is a fictional entity appearing in the Marvel Comics universe. It is a sentient, parasitic organism capable of infecting and controlling its hosts. Grevac typically targets intelligent beings, and once infected, the host's personality is suppressed, replaced by the Grevac's will. The infected individual often exhibits enhanced physical abilities and a heightened aggression. Grevac's origins are not fully detailed, but it is known to spread through direct contact or ingestion. Its primary goal appears to be self-propagation and the assimilation of new hosts.

Grevac has been depicted as a significant threat, often requiring the intervention of superheroes to contain its spread and rescue infected individuals. Its parasitic nature makes it difficult to combat, as it can operate from within its host, making it a stealthy and insidious adversary. Attempts to cure infected individuals are often complex, as the Grevac organism deeply integrates itself with the host's biology. Its presence in a story typically signifies a struggle for survival and the importance of maintaining individual consciousness against an overwhelming, invasive force.