Doctor Who: 10 Worst Things The Master Has Ever Done
3. Murdering One Tenth Of The Earth's Population
We could probably fill a whole article with the nasty stuff that the Master does during the Series 3 finale, because just when it seems like his evilness has peaked... he manages to push it to new heights.
For starters, the Derek Jacobi Master murders his kind-hearted alien assistant Chantho at the end of Utopia, before leaving the Doctor, Martha, and Captain Jack stranded in the year 100 trillion. And things only get worse from there.
After regenerating into John Simm, the Master - under the alias Harold Saxon - manages to become the UK's Prime Minister, and gleefully kills his entire Cabinet by gassing them to death. He later kills the American President too, before ordering his Toclafane murder-robots to slaughter one tenth of the Earth's population... and he does all of this with a big fat smile on his face.
In the next episode, he turns the Earth into a dystopia, ruling the planet with an iron fist and enslaving humanity for an entire year. Oh, and it's also revealed that he helped create the Toclafane, which are humans that have been stuffed inside metal shells.
Fortunately though, the Master's year as overlord of the Earth is completely erased from the timeline thanks to the Doctor and his allies, but this doesn't change the fact that the Master still did all that horrible stuff.