Doctor Who/Recap/S4 E2 The Tenth Planet

"Cyberman: Feelings? I do not understand that word.

The Doctor: Emotions. Love. Pride. Hate. Fear. Have you no emotions, sir?

Cyberman: Come to Mondas and you will have no need of emotions. You will become like us."

The TARDIS materialises at the South Pole in the far future of 1986, where a manned space probe is being talked down to Earth by a Space Tracking Station. The capsule is in difficulty, the Doctor realises, because of the gravitational pull of another planet that is moving toward Earth.

This planet turns out to be Mondas, Earth's "twin planet" from long ago, and is now the home of the Cybermen, a race of human-like beings who have over many centuries replaced their limbs and organs with metal and plastic. The Cybermen attack the tracking station while Mondas starts to drain Earth's energy. Ben stops General Cutler, in command of the station, from launching a powerful "Z-Bomb" to destroy the Cybermen and Mondas eventually disintegrates from absorbing too much energy.

The Cybermen are apparently entirely dependent on their planet, as once it is gone they all collapse and die.

The Doctor is also weakened and hurries back to the TARDIS, followed by Polly and Ben. Once inside, he collapses and the TARDIS takes off of its own accord. Before the humans' astonished eyes, the Doctor's face glows and becomes that of a completely different man...

The serial can be seen here. The episode with the Doctor's regeneration is, unfortunately, reduced to audio with stills and scene directions.

Tropes

 * AcCENT Upon the Wrong SylLABle - Theeee CYbermen have A biZARRE singSONG ACcent.
 * Apocalypse How - Somewhere between classes 4 and X, according to the Cybermen, although the Cybermen offer to rescue what humans they can as long as they accept Cyberconversion once they get to Mondas. Mondas itself suffers a Class X at the conclusion of the story.
 * Body Horror - The point of the Cybermen's cloth faces and bare arms.
 * Chest Blaster - Actually a gun kept on a chest bracket when not it use.
 * Creepy Monotone - Quasi-example: The Cybermen talk in bizarre, alternating, almost singsong tones, which nonetheless carry no emotion.
 * Culture Clash - The Cybermen genuinely don't understand why the Humans don't wish to cooperate with their plans.
 * Earthshattering Kaboom - The major threat for both planets during the final two episodes.
 * Exty Years From Now
 * Fake Shemp - The "Doctor passes out at the start of an episode for no clearly explained reason" plot device gets one last outing in this story. William Hartnell's health was in serious decline by this point, and they gave him a break for the third episode so that he'd be fully ready for his grand finale in the fourth. As a result, a body double plays him for the very brief moments we see him in the third episode.
 * General Ripper - General Cutler.
 * It Was His Sled - The Doctor regenerates.
 * The Nth Doctor - The first notable example.
 * Nuke'Em - Cutler's plan in Episode 3.
 * Well-Intentioned Extremist - How the Cybermen got the way they are.
 * Wham! Episode: Introduction of the Cybermen, regeneration debuts, William Hartnell leaves.