Yamadutas are messengers of Yama, the god of death in Hindu religion. It is believed that they arrive at the time of death of an individual on earth. Yamaduta follow orders and directions of Yama. They arrive to convey messages of Yama to mortals and to take them to his kingdom based on their deeds on earth.
When the time of an individual ends on earth, Yama sends one of his messengers to earth to take the individual to Yamaloka.
Details about Yamadutas, especially their features and weapons are mentioned in the Padma Purana.
Yamadutas are depicted with a rope and mace or club. Their faces are deformed. They have long teeth and their faces are like burning charcoal. They have huge figures. Their eyes burn like fire.
Crow is also referred as Yamaduta as it carries the food offered by relatives to dead ancestors.