Chupacabra is Spanish for Goat Sucker, and is a relatively new species, with reports dating back only as far as the late 80's from Central and Southern America, centering around Puerto Rico where it was first discovered.
The creature is reported to feed of livestock, particularly goats, draining blood from its victim. It is also reported to be around the size of a small bear, with spines on its head and back.
Several creatures have been sighted, and a few were shot and killed, however on examination they were found to be dogs or coyotes. The most famous creature was a coyote shot near San Antonio, Texas, which displayed sarcoptic mange (a flesh eating disease) which made the poor creature look unnatural or demonic. This creature is now referred to as the Elmendorf Creature.
The most common description given by eye witnesses is of a creature about the size of a small bear, with lizard like scales green/gray in appearance, with large dark eyes. Some also claim it has bat like wings.
Chupacabra has been popularised by the television show "X-Files", in which it featured in an episode entitled "El Mundo" in 1997.
It is widely accepted that this is a creature born from urban legends, no scientific evidence for its existence has ever been found.