4. Tsar Nicolas II Of Russia
There's a small theme here of royalty, but I think that they are the historical figures who people will know. Firstly, he technically isn't a Tsar, as Tsardom was ended in Russia in 1721 - Nicolas was 'Tsar' from 1894 to 1917. He also has a link with Queen Victoria by marriage, which we can see through the haemophilia link between European royalty - the Tsar's son Alexei had the 'royal disease' which Queen Victoria also carried. Seasoned viewers will already know this, as it was covered in the 2006 episode featuring Victoria herself - also claiming it arrived through a werewolf. Anyway, back to Nicolas, say it was the middle of the February 1917 revolution in Russia. He was determined to remain in power, so the Doctor takes him to see Russia in the aftermath of the revolution, which actually lasted over 50 years (or something like that). The city is in ruins, and there is an old man who looks like his father (actually him), who is left alone, abandoned by his children, and mourning his long dead son and heir. There is something living in the ruins too, which can only be defeated by Nicolas' abdication back in 1917. Obviously he eventually chooses abdication, and owes the Doctor his life, and his short happiness to live with his family.