Judoon

The Judoon are a race of rhinoceros-headed humanoids. They wear similar armour to the Sontaran's but have no obvious affiliations. The Judoon are "intergalactic Police-for-hire" and are hired by other alien races to track down certain targets and criminals. They have the ability to accuse, sentence and execute any criminal without trial. They were identified recently after transporting a London hospital to Earth's moon. (DW: Smith and Jones)