Nyssa

Nyssa — formally Nyssa of Traken or Nyssa, Daughter of Tremas and, on occasion, Nyssa Traken — was a companion of the Fourth and Fifth Doctors.

She was a native of the planet Traken, the capital of the Traken Union. She also travelled with Adric, Tegan, Turlough and Kamelion.

The daughter of Consul Tremas, Nyssa was a child of privilege on Traken. She was gifted with a brilliant intellect and specialised in bioelectronics. When Traken was destroyed, Nyssa became virtually the last of her kind and in the wake of the death of her father, the Fifth Doctor once said that he was "pledged to look after her."

She had at least two distinct periods of travelling with the Doctor. She initially travelled with him when she was barely more than a girl and left his company to help find a cure for Lazar's disease on the space station Terminus in the 35th century. She then rejoined the Doctor, Tegan and Turlough in her middle age, after becoming a wife and mother. She lost her life on the planet Apollyon in E-Space, after she sacrificed herself to allow the Doctor, Tegan and Turlough to return to N-Space after becoming trapped there.

As Traken nobility, Nyssa learnt manners and behaviours expected of her, while the servants' children were able to share rooms and play in the grounds. Both of her grandfathers died before she was born. (AUDIO: The Toy)

Nyssa first met the Doctor in his fourth incarnation when he was travelling with Adric. She had recently attended the wedding of her long-widowed father Tremas to Kassia. Unbeknownst to her, the Master had also come to Traken and was planning to exploit the tremendous power of the Keepership (to which her father was the only rightful heir) to live beyond his last natural regeneration. The Doctor and Adric stopped the Master from taking over the Keepership, but could not prevent him killing Nyssa's new stepmother. Unbeknownst to them at the time, the Master also killed Tremas by transferring his essence into Tremas' body, which left Nyssa orphaned in her young adulthood. (TV: The Keeper of Traken)

Soon after, the Watcher took Nyssa to the planet Logopolis. She discovered the Master had, in effect, killed her father. He enslaved her mind, involving her in his complex plan to conquer the universe. The Doctor soon broke her free of the Master's spell, then entered into an uneasy alliance with the Master. The two Time Lords and Tegan Jovanka rushed to Earth in the Master's TARDIS to halt the waves of rampant entropy the Master had unleashed upon the universe. Adric and Nyssa were left with the Doctor's TARDIS on Logopolis. The Watcher helped Adric transport the duo back to Earth. En route, Nyssa witnessed the entire Traken Union being swept away by the growing entropy field which threatened the existence of every part of N-Space. She knew she was the last of her entire species by the time the TARDIS materialised on Earth. When she next met the Doctor, he was mortally wounded in his successful battle to stop the Master. With assistance from the Watcher, he regenerated while Nyssa, Adric and Tegan looked on. (TV: Logopolis)