9. The Dominators - Part Five
If you thought Matt Smith firing a gun was bad, then prepare yourself for what Patrick Troughton did way back in 1968.
This Second Doctor serial pitted the Time Lord against the titular race, known for their use of nuclear radiation to power their technology. The Dominators plan to destroy the peaceful planet of Dulkis and use its remains as fuel, something that the Doctor, inevitably, doesn't take kindly to.
In fact, he takes so unkindly to it that he decides to obliterate them all with a nuclear weapon.
In the serial's final episode, the evil aliens attempt to blow up Dulkis using small atomic bombs called seeds. However, the Doctor manages to stop the seeds from entering the planet's core, and smuggles one back aboard the Dominators' ship.
The episode ends with the TARDIS flying away from a huge nuclear explosion that presumably killed every single Dominator onboard.
This level of rampant destruction is not something that modern fans would associate with the Doctor. Even at the time, this would've been considered a little over the top, especially with the real-world threat of nuclear devices looming large.