The Baak is perhaps the best-known monster of Assamese folklore. It inhabits swamps, lonely ponds, and abandoned temple tanks. It is constantly in search of fish.

In its natural form, a Baak appears as a very tall, lean, gangly, shadowy humanoid. It has long fingers and toes and messy hair, and it stinks like rotten seafood.

However, a Baak can change its shape. It can become a mist floating through swamp grass, with tendrils that reach out to snatch the catch from a fisherman’s boat. It can also take the shape of a human.

It is thought that in order to survive, a Baak needs to occupy a human corpse once in a while, drawing its energy from the dead. The more peaceable among the Baaks satisfy this need by inhabiting the bodies of the drowned, or of people who have been murdered and thrown in the water. Other Baaks have no compunctions about killing in order to obtain a fresh corpse.

A Baak always carries a small pouch or bag. This bag appears to be made of black fishnet, but it is really of some otherworldly material. If a person is able to steal a Baak’s bag, he will gain complete control of the monster. He can even make the Baak assume human form and work for him like a servant. However, the Baak will always be on the lookout for a chance to reclaim its bag, and if it does, then woe betide the thief!

There is substantial overlap between legends of the Doht, the Ghorapaak, and the Baak. These may all be different names for the same creature, or they may be related varieties.