The Tenth Doctor's (David Tennant) third companion Donna Noble (Catherine Tate) was one of the fiercest and funniest characters on Doctor Who. Donna Noble outwitted Daleks, solved mysteries with Agatha Christie, and saved the entire universe on multiple occasions. Although Donna was only a companion for one season, she will be forever be remembered in Doctor Who as the most important woman in the whole of creation. Tragically, Donna never knew how important she was.
In Doctor Who season 4, episode 13, “Journey’s End” Donna Noble absorbed the Doctor’s regeneration energy and gained the knowledge of the Time Lords. She used these skills to stop Davros from destroying the universe and returned everyone safely home. Afterward, Donna's human mind was overwhelmed so the Doctor erased all of her memories of their adventures in order to save her life. From then on if she ever remembered anything about the Doctor her mind would burn and she would die. She then lived out a normal life, never to travel the universe again. Donna's exit has gone down in Doctor Who history as one of the most tragic character departures, almost as tragic as The Tenth Doctor's ending.
Related: Doctor Who: Is Chibnall Stealing The Tenth Doctor’s Ending?
What separated Donna’s departure as particularly tragic on a show full of heartbreaking character exits is that she didn’t choose her fate it was chosen for her. Every other companion who traveled with the Tenth Doctor got some say in their fate, except Donna. Rose Tyler chose to return to the alternate dimension with her clone of the Doctor, Martha Jones left to join UNIT, but Donna begged and pleaded not to be returned to her former state. the Doctor chose to erase Donna's memory so she lost her
Read more on screenrant.com