The Doctor is one and many. With each regeneration, they don’t just take on a different face but different ideas and ideals.

The two-parter "The Zygon Invasion" / "The Zygon Inversion" featured The Doctor and UNIT trying to stop the radicalization of a young sect of Zygons living secretly on earth, in a clear allegory ...

Planet of Evil: Part 3—Season 13, Planet of Evil: Part 3 Planet of Evil: Part 2—Season 13, Planet of Evil: Part 2 Planet of Evil: Part 1—Season 13, Planet of ...

The Zygons debuted in this adventure and flashbacks aside, they subsequently remained unseen for decades. During their ‘hiatus’ they remained a popular foe amongst Doctor Who enthusiasts.