Cass Fermazzi

Cass Fermazzi (PROSE: The Day of the Doctor) was the sole remaining pilot of a space gunship. She died when the ship crash-landed on the planet Karn, choosing death over being rescued by the Eighth Doctor, a Time Lord. (TV: The Night of the Doctor)

Early life
Cass grew up on one of the farm planets of the Gazrond Belt. She spent some of her childhood in therapy, being given a robot clown to help take her memories. The clown did not work, as it was already full of someone else's memories. The robot told her to fight for what's right, and never be cruel or cowardly. Cass listened to the robot's advice, and, at the age of fourteen, she stowed away on a star freighter to see the universe. (PROSE: The Day of the Doctor)

Fighting in the Time War
However, she became trapped in the Last Great Time War, and did her best to avoid the conflict. However, after witnessing the death of an old soldier, she realized she had nowhere to run and instead chose to fight after a medtech gave her the dead soldier's bandolier.

She crewed a gunship for four years, surviving the Nightmare Child, seeing the massacre of Skull Moon, and fighting in the ruins of the Ulterium. (PROSE: The Day of the Doctor)

Death
One day, Cass and her crew fought off a Dalek fleet from the feeding hives of the Vantross, but they were then attacked by a Time Lord battle cruiser that was frustrated Cass had gotten between them and the Daleks. (PROSE: The Day of the Doctor)

As the only one who wasn't panicking, Cass teleported the rest of the crew off the ship onto the nearest planet. (TV: The Night of the Doctor) Once she realised a safe crash-landing wasn't an option, (PROSE: The Day of the Doctor) Cass made a call for help, which was picked up by the Eighth Doctor. He materialised his TARDIS on board and tried to rescue Cass, but, recognising him as a Time Lord, she deadlocked the Doctor on the other side of the door from her, professing that the Time Lords were no different from the Daleks. The Doctor refused to leave her side, even when it meant he would also be killed in the crash. The ship crashed into the surface of Karn in a massive explosion, killing both Cass and the Doctor. (TV: The Night of the Doctor)

Post-mortem
Though their bodies was recovered by the Sisterhood of Karn, and they were able to revive the Doctor, Cass's injuries were too severe for even the Elixir of Life to heal. Cass's death was the catalyst for the Doctor to finally take part in the war, and he chose to regenerate into a warrior, who immediately claimed her bandolier as a reminder of what he would be fighting for. (TV: The Night of the Doctor) After some time searching for them, he was able to return Cass's body to her family. (PROSE: The Day of the Doctor)

Cass Fermazzi Cass Fermazziová