Nyssa — formally Nyssa of Traken or Nyssa, Daughter of Tremas, and on occasion Nyssa Traken — was a native of the planet Traken, the capital of the Traken Union. She was a companion of the Doctor for a brief period towards the end of his fourth incarnation and travelled with him for much of his fifth incarnation. She also traveled with Adric, Tegan Jovanka, and Turlough.
The daughter of Consul Tremas, Nyssa was a child of privilege on Traken. She was gifted with a brilliant intellect and specialized in bio-electronics. When Traken was destroyed, Nyssa became virtually the last of her kind, (TV: Logopolis) and in the wake of the death of her father, the Fifth Doctor once said that he was “pledged to look after her.” (AUDIO: Primeval)
She had at least two distinct periods of travelling with the Doctor. She initially traveled with him when she was barely more than a girl, and left his company to help at what was effectively a leper colony on Terminus in the 35th century. (TV:Terminus) She then rejoined the Doctor, Tegan and Turlough in her middle age, after becoming a wife and mother. (AUDIO:Cobwebs)
Nyssa seemed at once more mature and more naive than her fellow travelers. She did not boast of her scientific knowledge nor believe it made her superior. She faced her challenges with the determination and serenity of her Trakenite heritage. She turned her sorrow as the last of her people into a desire to help others. Rarely did she mention any grief she suffered because of her great misfortunes. Perhaps most extraordinarily, she never sought to avenge herself on the Master despite her many good reasons to do so.
Tegan noted that Nyssa preferred to “care and share.” (PROSE: Goth Opera) Her trusting nature sometimes made her less alert to deception than Tegan (TV: Mawdryn Undead) but it also made her more adept at negotiating an effective balance between strong personalities. (TV: Earthshock, AUDIO: The Game) She had probably the closest relationship with the Fifth Doctor of any of his companions. Nyssa’s near-royal upbringing and natural curiosity sometimes made it hard for her to relax and enjoy herself. Though her outlook usually tended to be serious, she displayed a dry wit on occasion, particularly when dealing with the Doctor’s boyish idiosyncrasies.
Like all Trakenites, she tended towards pacifism, though on separate occasions she destroyed a Terileptil android in September 1666 (TV: The Visitation), killed a Cyberman in the TARDIS (TV: Earthshock) and used the threat of violence to save the Doctor’s life, shooting a pair of guards on Gallifrey. (TV: Arc of Infinity)
She considered Tegan to be her best friend. (AUDIO: The Emerald Tiger). However, she also “never quite understood” why so many of the Doctor’s friends were human. (AUDIO: The Boy That Time Forgot)
Nyssa generally didn’t use a surname, referring to herself only by the mononym “Nyssa” or, in formal circumstances, “Nyssa of Traken” or “Nyssa, daughter of Tremas.” When posing as a human actor, however, she assumed the name “Nyssa Traken.” (AUDIO: Special Features)