Plasmavore

The Plasmavores were a race of blood-sucking near-Humans. They were commonly criminals, murdering people across the universe and drinking their blood.

They required plenty of blood to surive as their bodies absorbed a lot of salt. The fact that they were near-Human helped them in hiding, as they could blend in with Humans on Earth, and when they drank Human blood, they could assimilate it into their own systems and fool a Judoon alien scanner, however she could not assimilate Gallifreyan blood, and thus if they drunk a Gallifreyan's blood the Judoon scanners would not be fooled. One Plasmavore, going by the name of "Florence", was executed by the Judoon because of this.

Some Plasmavore criminals made use of Slabs to restrain their victims before killing them. (DW: Smith and Jones)