Aswang are vampiric ghouls from Fillipino culture. Some are rumored to be shapeshifters, and are believed to have interacted with humans on a social basis.
They are day-time creatures, and are considered sentient and often, very intelligent. Like most unholy creatures, they are weak against holy magic and items, such as holy water.
Some say that you can tell if a humanoid is an aswang by looking into their eyes. If your reflection is upside down, you may be sure that you are not dealing with a human!