The Master {Simm}

An insane Time Lord and old friend turned archenemy of the Doctor, the Master used hypnotism and deception to ensure his election as Prime Minister of the United Kingdom under the human alias of "Harold Saxon", which was his first step towards conquering the Earth and creating a new Gallifrey from it. He is known for being unique amongst other incarnations of The Master due to his genuine hatred and disgust of The Doctor where other incarnations can at least tolerate or enjoy his presence, either for fun or due to lingering feelings of friendship towards their old friend. He is also one of the most unhinged incarnations to date, likely due to the "never-ending drumbeat" he hears in his head. Unlike other incarnations in the Revival Series, the "Harold Saxon" Master is an unfathomably cruel, selfish psychopath with no redeeming qualities. After successfully conquering Earth, the Master orders the population to be decimated for no other reason than to satisfy his own violent impulses. He was extremely vain and narcissistic, with the Tenth Doctor noting that he would never destroy himself, even if he could destroy the Earth with him. During the Year That Never Was, he had monuments of himself built all over Earth, and, according to Martha Jones, had even sculptured himself onto Mount Rushmore. He also used the Immortality Gate to turn the human race into duplicates of himself, which he dubbed the "Master Race", and also threatened to do the same to the Time Lords, even asserting that Rassilon "[would] [look] better as [him]." "Harold Saxon"'s vanity was so vast that when the Tenth Doctor forgave him for his actions, the Master collapsed and wept out of shame. After he expressed revulsion at being "kept" by the Doctor, the Master was shot by Lucy and decided not to regenerate and die to spite the Doctor. He even killed Missy, his future incarnation, when she decided to help the Twelfth Doctor. "Harold Saxon" is the 18th Incarnation of the Master. The Master has powers and skills like that of any Timelord but additionally, he has the abilities of Genius-level intelligence, the ability to regenerate, the use of a laser screwdriver, the loyalty of the Toclafane, perception filter, hypnotism, disguise, and natural charm and charisma. For a bit of time temporarily, he even had the ability to shoot lightnight out of his hands. He is a known renegade criminal of Gallifrey, having committed crimes of Genocide, Theft, Breaking and entering, Abuse of power, Mass murder, Torture, Assault, Subjecting people to a fate worse than death, Incrimination, War crimes, Kidnapping, and much more.