Translated literally from Spanish as "goat-sucker" (compare with chotacabras, the nightjar), the chupacabra is said to attack small livestock and drink their blood. Descriptions of this creature vary, and no one has produced undisputable evidence of its existence.
Chupacabra are said to prominently appear in two specific forms. The first: a lizard-like being, appearing to have leathery/scaley greenish skin and sharp spines running down its back. It stands approximately 3-4 feet high, and stands/hops in a similar fashion as a kangaroo (in at least one sighting, the creature hopped 20 feet). This variety is said to have a sort of proboscis extending from its mouth, with a forked tongue protruding from it.
The second variety also stands/hops as a kangaroo, and it has coarse fur with greyish facial hair. The head is similar to a dog's, and its mouth has large teeth.
Some believe the chupacabra is a product of "social hysteria" while others feel this is a weak explanation for the real dead animals resulting from the creature's unexplained attacks. There are many eye-witness accounts dating back many years.
A few pictures which may be hoaxes (link below) exist of the Chupacabra.