Xenomorph
The term Xenomorph originates from the Alien series of movies. In the films the Xenomorph is an alien that gestates within a living host for a number of hours (or days).It then emerges from the host (killing it in the process) and begins a rapid process of growth, increase in size from approximately 30 cm to over 6ft in an hour or so.
The Xenomorph is reknowned for its intelligence and agressive behaviour. Social structures tend to follow a hive mentality with drones serving a single queen.
Biologically they are remarkable with no visible eyes and molecular acid for blood. There is also a laval stage, denoted by the presence of a facehugger, which impregnates the host.