The Kaliratha were a vampiric species; they feed off the dead, and would kill to feed on their souls. Kali was their leader. A family was so loyal to them, that their own DNA was laced with Kali's own, allowing them a demonic transformation. They tried to invade Earth in the 24th century, but were defeated by the Twelfth Doctor. (COMIC: The Swords of Kali)
Behind the scenes
In practical terms, the Kaliratha appeared to have been based on Vetala, demons assosiated with Kali .