Doctor Who:Four Times The Doctor Has Lost Friends To The Cybermen

'Ascension Of The Cybermen', the first part of the promised epic two-part finale for Doctor Who series 12, has left fans on a massive cliffhanger, with The Master returning once again, the mysterious 'Boundary' appearing to be a portal to Gallifrey, and Graham and Yaz left to what seems to be certain doom, trapped aboard a Cyber-Warship with the Lone Cyberman and his army.

While we'd like to think The Doctor's beloved companions will pull off a miraculous last minute escape, this is far from a certainty. While the Cybermen usually rank below the Daleks when it comes to The Doctor's rogue's gallery, they have a scarily impressive record when it comes to harming people The Doctor cares about.

Here are four times The Doctor has lost friends to the Cybermen.

1. Adric (Earthshock)

Perhaps the most infamous example of The Doctor losing a loved one to the Cybermen is the death of Adric in the classic Fifth Doctor story, 'Earthshock'. The Cybermen have set a space freighter loaded with anti-matter bombs on a collision course with Earth. Adric stays behind on the freighter to try and stop the collision, but fails, and is tragically killed in the explosion that follows. Thanks to a bit of accidental time travel, the freighter turns out to be the 'meteor' that killed the dinosaurs, making Adric's death a fixed point, with no way for The Doctor to save him.

Adric's death deeply affects his fellow companions, Nyssa and Tegan, and haunts the Fifth Doctor for the remainder of that incarnation's life. Adric's name is the Fifth Doctor's final word before he regenerates.

2. 'Pete's World' Jackie Tyler ('Rise Of The Cybermen/The Age Of Steel

The first appearance of the Cybermen in the Doctor Who revival came in the series two two-parter 'Rise Of The Cybermen/'The Age Of Steel'. The Tenth Doctor, Rose Tyler, and Mickey Smith travel to a parallel universe where Rose's Father, Pete, is still alive, and a successful businessman. The Cybermen, brainchild of the insane John Lumic in this reality, crash the alternate Jackie Tyler's Birthday Party. Jackie is quickly captured, becoming one of the first in 'Pete's World' to be converted into a Cyberman.

While The Doctor attempts to reassure Rose that this is not the same version of her Mother that they know and love, Rose is still troubled by the alternate Jackie's tragic fate.

3. Danny Pink (Death In Heaven)

In the final two episodes of series eight, the Twelfth Doctor and Clara journey to the afterlife in the hope of resurrecting Clara's recently deceased boyfriend, Danny. Unfortunately, Danny becomes a victim of Missy's evil plan to raise all the Earth's dead as Cybermen. However, Danny, whose emotional inhibitor failed to activate upon his own conversion, is given one final chance to be a hero when he leads the other newborn Cybermen to destroy the Cyber-cloud and save Earth. While he is given an opportunity to return to life, he gives it up in favour of saving a young boy whom he had accidentally killed during his time as a soldier.

Danny's death has far reaching consequences, loosening Clara's ties to her human life which leads to her increasingly reckless behaviour and eventual death in series nine.

4. Bill Potts (World Enough And Time/The Doctor Falls)

After spending the first half of series ten's two-part finale trying to rescue his much-loved companion Bill from aboard a mysterious ship, the Twelfth Doctor is devastated to discover that Bill has been converted into one of the very creepy Mondasian Cybermen. Bill is able to fight her programming enough to maintain her individuality. Unfortunately, this also comes with an awareness that life as a Cyberman is really no way to live. So, The Doctor reluctantly allows Cyber-Bill to accompany him on what they both believe to be a suicide mission.

This is a slightly less tragic example, seeing as how Bill is ultimately saved, and restored in some fashion, by Heather, and the Target novelisation of 'Twice Upon A Time' reveals that the pair did eventually return to Earth and live a full human life. However, the story still holds an element of sadness in the fact that although The Doctor does learn that Bill was saved, he never quite lets himself believe it. That, and knowing that she was restored doesn't change the fact that he had been unable to save her himself. This failure to protect Bill still affects The Doctor, as we saw last week in 'The Haunting Of Villa Diodati'.

Hopefully, the Thirteenth Doctor's companions can avoid becoming a part of The Cybermen's deadly legacy. But with Jodie Whittaker the only cast member confirmed for series 13 so far, and exit rumours swirling around certain companions, we should probably prepare ourselves to lose at least one.