Soulless are a very depressing form of undead; they are people who have lost their souls through various means, and they lose all that made them themselves. It is like they are completely wiped of their personality and self. They may follow orders, but they do not behave consciously, and must be told word for word what to do and be helped throughout the process.
They have often been compared to zombies, due to the lack of function in their vital organs that stops them from being killed through methods such as drowning or bleeding out, but more accurately the two forms of undead are opposites; as zombies are caused by the soul remaining in the body after death, instead of the soul being removed before death.
It would be more accurate to compare the soulless to a reanimated corpse; however, unlike these corpses, soulless people’s bodies do not decay around them.
Tests done by the Coto government during the lead-up to their civil war discovered that minor trauma directly to the brain that would usually cause the death of a conscious person doesn’t seem to effect the functions of a soulless. It is known that this research led the Coto government to obtain a way to turn people soulless, and this threat was used heavily to keep their populace under control. However, information on the methods of creating soulless was destroyed by Colla’colkort after the war ended to prevent the slave-trade from reemerging.
Currently, one of the only known ways for a person to be turned soulless is through a basilisk attack.