Corakinus Corakinus was the Shadow King of the Shadow Kin and leader of the War of the Underneath . ( TV : " For Tonight We Might Die " , " Co - Owner of a Lonely Heart " ) He ruled from the Shadow Palace . ( TV : " Co - Owner of a Lonely Heart " ) In 2016 , he began sharing his heart with April MacLean , ( TV : " For Tonight We Might Die " ) who later defeated him in battle and took his place as Shadow King . ( TV : " Brave - ish Heart " ) After getting his title back , Corakinus and his entire race was killed by Charlie Smith , using the Cabinet of Souls , and April took over his body . ( TV : " The Lost " ) Biography . After wiping out the population of Rhodia , Corakinus pursued the Rhodian prince Charlie and his Quill bodyguard Miss Quill to ensure that Charlie could not use the Cabinet of Souls to exact revenge on the Shadow Kin . He tracked them to the Coal Hill Academy on Earth , where he led the Shadow Kin in an attack on the fugitives . Ruthless in his hunt for the prince , Corakinus kill ed Rachel Chapman 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 " ) Upon returning to the Underneath , Corakinus was wracked with paranoia . He was supposed to be seen as a leader and a warrior , someone who would guide his people into battle but he carried the shame of being trapped into sharing the heart of a human schoolgirl . Corakinus sought out medical help and assistance from other members of the Shadow Kin . Unfortunately for him however , none of the practices helped break his connection with April and he ended up killing all those who failed to find him a solution . Back on Earth , his constant experiments in meddling with their shared heart caused April to become more outlandish — alerting her new partner Ram to the dangers of the Shadow Kin ' s return . Eventually , Corakinus was able to locate April — feeling that the only way to break their connection was to kill her . Corakinus opened a crack in time which led to April ' s back garden and April , along with Ram , entered with the desire of killing him before he killed her . ( TV : " Co - Owner of a Lonely Heart " ) After reaching the Shadow Palace , April challenged Corakinus to a duel . They fought using their scimitars and in the end April beat Corakinus but decided to spare his life as they still shared a heart . April announced that she didn ' t need to kill Corakinus as the rest of the Shadow Kin had already seen her defeat him and therefore she would be proclaimed the new King . Using her new army , April had Corakinus imprisoned . While imprisoned Corakinus removed the anchor between his and April ' s hearts , meaning that while they were still connected the connection was weaker . ( TV : " Brave - ish Heart " ) Due to April neglecting her role as King of the Shadow Kin it wasn ' t hard for Corakinus to reclaim the title . In control of his army again he decided that it was time to destroy his enemies by letting the Shadow Kin kill everyone on Earth . However , to do this he needed to make sure that April was safe - as she still shared a heart with him . In order to force April into giving herself up he decided to begin executing the gang ' s closest family members . He executed Ram ' s father Varun and Tanya ' s mother Vivian . He even tried to kill April ' s mother Jackie MacLean but due to her having part of his soul inside her he couldn ' t . After a stand off , Corakinus put a shadow onto Charlie ' s heart . He later went on to attack Jarvis and Damon Adeola , but was prevented from killing them by a heavily pregnant Quill . After this he captured Matteusz Andrzejewski and used him as a bargaining chip to get April to come with him . She agreed and was in his grasp , but she found out his true plans to kill the human race . Charlie shot April and , as they both shared the same heart , Corakinus died too . This led to Charlie becoming the Shadow King . After Charlie used the Cabinet of Souls to destroy all of the Shadow Kin , April was resurrected in Corakinus ' body . ( TV : " The Lost " )