10 Most Heartbreaking Doctor Who Moments
8. Bill Potts Cries
After the loss of Clara, we are introduced to Bill Potts. She becomes the Twelfth Doctor's companion until, whilst attempting to reform Missy, she was mortally wounded.
Knowing he cannot save her, the Doctor lets her be taken away in an attempt to save her life. During an attempt to rescue her, Twelve comes face to face with a fresh Cyberman who recognises him as the Doctor. He asks where Bill Potts is and the Cyberman tells him it is Bill Potts. Tragically saying "I waited for you", and letting loose one single tear.
In the next episode, we see Cyberman-Bill appearing from a spaceship carrying an unconscious Doctor in her arms. We jump forward two weeks and Bill is in a barn, a woman brings her blankets but is fearful of Bill, who believes she is still human and cannot see her cyber self.
Bill and the Doctor stand against the Cybermen so everyone can escape, she finds his body and weeps over him. She connects to Heather, a sentient oil creature, Bill becomes like her and goes with her on another adventure, leaving the Doctor to regenerate.