|Purpose||To convince against abortion|
While various legends have slightly different versions of the tiyanak folklore, the stories all agree on its ability to mimic an infant, with its ability to imitate an infant's cries for luring victims. In some legends, the Tiyanak may take the form of a specific child.
- In one version, it retains the general shape of a baby but then forms sharp claws and fangs to attack its victim.
- In another, it shares certain similarities with dwarfs and is similarly associated with the earth. In this version, the "true" form of the tiyanak is that of a little old man with wrinkled skin, a long beard and mustache, a flat nose and eyes the size of peseta coins. The same story says that a tiyanak is relatively immobile because its right leg is much shorter than the other. This deformity forces it to move by leaping rather than walking, making it difficult to hunt or stalk victims, but its ability to mimic an infant's cry compensates for this disadvantage.
- In yet another story it is seen supernaturally flying through the forest (still in the form of a baby) and in a legend from the island of Mindoro it transforms into a black bird before flying away.
- In another version from Pampanga, the tiyanak are described as small, nut-brown people who don't walk on the ground but rather float on air. They have large noses, wide mouths, large fierce eyes and sharp voices.
It usually takes the form of a newborn baby and cries like one in the jungle to attract unwary travelers.
Once it is picked up by the victim, it reverts to its true form and attacks the victim. The tiyanak is also depicted to take malevolent delight in leading travelers astray, or in abducting children.
There are various stories on how tiyanaks came to being. The Mandaya people of Mindanao claim that the tiyanak is the spirit of a child whose mother died before giving birth. This caused it to be "born in the ground", thus gaining its current state. A similar supernatural creature in Malay folklore is the Pontianak, which was a woman who died before giving birth.
With the Spanish colonization of the Philippines in the 16th century, the tiyanak myth was integrated into Christianity. The tiyanak in the Christian version were supposedly the souls of infants that died before being baptized. In modern-day Philippines, this definition has extended to that of aborted fetuses that returned from death to seek revenge on those who deprived them of life.