The crow is a supernatural bird that serves as the protagonists' link between the living world and the realm of the dead. The magical crow is capable of resurrecting people who have been unjustly murdered and/or have left behind with a terrible sadness that prevents their soul from resting, so that person may be able to seek vengeance on the person or people responsible for their death and suffering.
During the person's "rebirth", the crow serves as a spiritual guide, helping the individual tap into his or her potential and assisting in tracking down the wrongdoers. To other people, the crow seems to be nothing more than a common bird, but the crow is capable of speaking to the reborn, often helping guide them to exact their revenge.
If the crow is harmed or killed, the reborn person becomes vulnerable. However, the crow also seems to be much more enduring than a regular bird and might possess some regeneration abilities. For example, in the 1994 movie The Crow, the bird survives after being shot with a rifle.