Corakinus

Corakinus, also known as the Shadow King, was the King of the Shadow Kin.

Having wiped out the population of Rhodia, Corakinus followed the Rhodian prince Charlie and Quill to Earth where he led the Shadow Kin as they attacked the Coal Hill Academy where the two fugitives were hiding. Ruthless in his hunt for the prince, Corakinus killed Rachel without provocation and severed Ram Singh's leg when he attacked him.

Miss Quill instructed April MacLean to fire a displacement gun, but Charlie knocked her out of the way so it wouldn't kill her. The gun hit Corakinus' heart, scattering it across the universe, but he kept on living, sharing April's heart.

Corakinus was ultimately confronted by the Twelfth Doctor, who had been summoned for help by Quill, having been the one who relocated her and Charlie. When the Doctor used the Shadow Kin's aversion to light against them, Corakinus and his force were forced back through the tear in space-time from where they came which the Doctor subsequently sealed. Corakinus warned, however, that he would later return. (TV: For Tonight We Might Die)