Sri Yamaraja is the the brother of Saturn or Sri Sanaiscarya, and Yamaraj is not only the Lord of Dharma, but also the Lord of Death. He is often referred to in Sastra as the officer you will meet after dieing, who will judge your life and grant your next placement.
He has servitors known as the Yamaduttas. Dutta means messenger, and Yama means Lord of Death. So, they are the "messengers of the Lord of Death"