10 Doctor Who Villains Who Should NEVER Return

The Family of Blood were a group of malevolent aliens who had chased the Doctor (played by David Tennant at the time) and his companion Martha through time and space, seeking the Time Lord's life force in a quest for immortality. In order to escape them, the Doctor was forced to turn himself into a human using a Chameleon Arch in the TARDIS, disguising his Time Lord biology and changing him into the school teacher John Smith, who worked at a boy's school in rural England 1913.

Though we never see their true form, the Family track the Doctor to his last location and possess the local villagers. It's all in the performances by the actors that bring these terrifying creatures to life, as while on the outside they appear human, it's their facial expressions and mannerisms that make them such a disturbing presence- and that's before they animate an army of scarecrows and possess a little girl who has an IT-style balloon.

Their terrorism of the Doctor and attacking both the village and the school makes for some great acting and terrific script-writing, as the Doctor does not know that he is in fact a Time Lord due to the Chameleon Arch, adding a real sense of peril and danger to the story.

By the end, the Doctor imprisons each of the Family, granting them immortality, but not in the manner that they wished for. It's a terrific two-part from Russell T Davies and to bring these villains back after such a perfect outing would risk ruining the impact that they brought in the beginning.