10 Doctor Who Villains Who Ultimately Turned Good

Like The Empty Child, Noah - or Lazar, to give him his proper name - started out good, was transformed into a baddie, and then turned good once again.

Leader of a group of humans onboard the space station in the Fourth Doctor serial Ark in Space, Noah is woken from suspended animation at the start of the second episode, and even though he's rude towards the Doctor (and he stuns him with a gun), it's clear that he's a decent guy who just wants the best for his people.

Shortly afterwards, Noah is infected by the Wirrn - which are basically a race of space insects - and he turns violent, killing Libri, a station engineer. His body then starts to turn green as the infection spreads (conveyed with some not-so-convincing bubble wrap "special effects"), and eventually, he is transformed into a full-on adult Wirrn.

But Noah still has some good left in him. The serial concludes with him leading the Wirrn swarm into a shuttle and blowing it up: in the end, Noah's humanity prevailed.