They are giant skeletons said to be fifteen times the size of a regular human being (roughly 90 feet tall), though they are usually pictured only from the waist up. There are no ligaments or muscles linking the bones, which can only be assumed to be held together through some sort of "magic".
They are sometimes shown as having no eyes, but just as often they are shown with regular eyeballs, red eyes or a "glow" or flame instead of proper eyeballs. Gashadokuro sometimes also possess a very long tongue. It's also said that, as their rage grows brighter, their bodies will be engulfed with flames.
They are said to be vicious, hungry stalkers of the night who live on the sheer anger and hatred that summoned them.
Also known as "Odokuro", Gashadokuro stalk lone Humans at night (mostly travellers on empty roads) and attempt to grab them and bite their head off, then suck all the blood out of their body. Gashadokuro are created from gathering bones from people who have died of starvation or warfare. The only way a Gashadokuro can be detected before it appears is by hearing a ringing in one's ears, or the grinding of their giant teeth.