From WikiPilipinas: The Hip 'n Free Philippine Encyclopedia
The sigbin is a creature in Philippine mythology that walks backwards with its head lowered between its hind legs, and sucks the blood of its victims through their shadows. It is usually believed to be nocturnal, and to reside in the province of Cebu.
 Description and habits
The sigbin is sometimes described as resembling a kangaroo, with its forelegs shorter than the hind ones and its fan-like ears making a flapping sound while walking. Its long flexible tail is said to be used to whip its victims while emitting a very stinky odor. It usually lurks at night in barrios, looking for unattended children and devouring them to make an amulet or charm from the child's heart. It is said that they are difficult to find because they have the ability to become invisible, especially in the presence of humans. Some who claim to have seen these creatures say it looks like a hornless goat, while some say it resembles a monstrous crow, with two long legs under its neck like those of a grasshopper, enabling it to leap great distances without using its wings.
Some believe that the creature can be stored in a jar or banga. Families known as "Sigbinan", or those who own sigbins, have the power to to command the creatures who bring wealth and luck to the owners, especially to businessmen.
Some say that the sigbin is a spiritual animal with no physical form, which could be the reason for the varying or conflicting descriptions, and the lack of concrete evidence of its existence. Stories of old folks regarding the sigbin are usually found in Visayas, especially in Cebu. In the Eastern Visayas, the creature is also known as the Amamayong. Other countries have reports or urban legends of similar creatures, known as "chupacabra".
 Speculations on sightings
A carnivore not previously known to science was discovered in 2005 on the island of Borneo. Described as a "cat-fox", it has hind legs that are lower than its front legs. It is speculated that this species could be the original basis of the sigbin legends. Others have speculated in the past that there could be an actual "sigbin" animal, possibly related to the kangaroo.
 Popular culture
The sigbin is the subject of the song, "Original Sigbin", popularized by the Visayan band, Junior Kilat.