The Douwds are a species made of pure energy. Each being is immortal and of multiple appearances. They can thus take the human appearance. They can create objects such as houses, invincible spaceships, but also living beings.
They have an extraordinary power of destruction.
They can use psychic powers to attack their enemies.
If they can create, they are incapable of resuscitating living beings, unlike the organians, only to recreate them. They are omnipotent, but not omniscient.
Their world of origin is unknown.
The only Douwd Starfleet met was Kevin Uxbridge. He had been in the Milky Way for at least several thousand years. He was guilty of eradicating the Husnocks, a destructive species, with its population of 50 billion. The Husnocks were responsible for the death of his wife.