Nyssa

Nyssa (formally, Nyssa of Traken and rarely, Nyssa Traken) was a native of the planet Traken, the homeworld of the Traken Union. She was acquainted with the Fourth Doctor, but was mainly a companion of the Fifth Doctor. She also adventured with Adric, Tegan and, briefly, Turlough and the Brigadier.

The daughter of Consul Tremas, Nyssa was a child of privilege on Traken. She was gifted with a brilliant intellect, and specialized in bioelectronics.

Initial encounter with the Doctor
Nyssa first met the Doctor in his fourth incarnation when he was traveling with Adric. She was preparing to celebrate the marriage of her long-widowed father 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. One of his goals in doing so was to live beyond his last natural regeneration. The Doctor and Adric prevented the Master from taking over the Keepership, but could not prevent his killing Nyssa's new step-mother. They also did not stop the Master from "killing" Tremas by transferring his essence into Tremas' body. The Master lived, and Nyssa was orphaned in her young adulthood. (DW: The Keeper of Traken)

Travels
Soon after, the Watcher transported Nyssa to the planet Logopolis in the Doctor's TARDIS. There, 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, but immediately entered into an uneasy alliance with the Master. The two Time Lords and Tegan rushed back 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 learned the entire Traken Union had been 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 materialized on Earth.

When she next met the Doctor, he was mortally wounded in his successful battle to stop the Master. He regenerated, never having travelled with her in the TARDIS. (DW: Logopolis) Because of the Doctor's debilitated state after his fourth regeneration, Nyssa helped him get to the TARDIS before the Pharos Project's security guards could arrest them for trespassing. Once in the TARDIS, she became even more worried; the Doctor and Adric were lost in the corridors. When she caught up to them, she found he had changed his outfit and was desperately looking for the Zero Room to recover. However, once the Doctor was in the Zero Room, she found the TARDIS had traveled back to the beginning of time. They were about to be blown to apart by the Big Bang. Managing to get the Doctor stable long enough to figure out how to escape, Nyssa accidently ejected the Zero Room to give the TARDIS enough thrust to go forward in time. Arriving at Castovalva, Nyssa found it was a secondary trap by the Master to get rid of the Doctor by using Adric to make block transfer computations. However, they escaped Castravalva with Adric and the Doctor stablized. They then began traveling; she no longer had a home to go to except for the TARDIS. (DW: Castrovalva)

Arriving on an Urbankan ship, Nyssa was taken by the android inhabitants to become one of their own. The Doctor and Bigon rescued her. Nyssa fainted (DW: Four to Doomsday) from stress. She could not concentrate; she could not match Adric at chess. The Doctor made a device to let her sleep and recover. Nyssa awoke four days later to discover that the Doctor had had an adventure without her. (DW: Kinda) Thereafter, she discovered she had a look-alike by the name of Ann Talbot in early 20th century England. The two attended a costume party in the same dress, making it impossible to tell them apart. George Cranleigh kidnapped Nyssa by mistake, but released her to the Doctor when he discovered his mistake. (DW: Black Orchid)

Nyssa encounter Cybermen trying to attack Earth, but watched as they were foiled by Adric. Nyssa was horrified to see Adric give his life to stop the freighter that killed the dinosaurs. (DW: Earthshock) Adric's death was a severe blow to Nyssa and Tegan. While working through their grief, the TARDIS crew was embroiled in an adventure which sent a Concorde back through time. After they returned the aeroplane to 1980s Heathrow Airport, the Doctor accidentally left Tegan behind as she wished to continue travels with them. (DW: Time-Flight)

Nyssa and the Doctor began traveling alone together. Nyssa began to develop her nascent telepathic powers (BFA: Winter for the Adept, Primeval). She also witnessed the birth of the Cybermen on Mondas. (BFA: Spare Parts) For a time, the Doctor and she were joined by Thomas Brewster, a human male from Victorian London. (BFA: The Haunting of Thomas Brewster) This threesome had a few adventures — perhaps most notably one in which Nyssa discovered Adric had not died in Earth's prehistoric past (BFA: The Boy that Time Forgot) — before Thomas left the TARDIS to pursue a romance in 2008. (BFA: A Perfect World) Nyssa continued traveling alone with the Doctor until they chanced upon Tegan in Amsterdam. During the same adventure, she forcefully stood up to the Gallifreyan High Council on the Doctor's behalf. She encounter Omega, who wished to bond with the Doctor to escape the anti-matter universe, but was successful in helping the Doctor prevent this. (DW: Arc of Infinity) Soon after, Nyssa discovered that Tegan was still aflicted by the remnants of the Mara from the Kinda world and helped the Doctor take her to Manussa to permanantly destroy the Mara with a "snakedance". (DW: Snakedance) She mistook Mawdryn for the Doctor going through a gruesome regeneration and was infected by his disease. The Doctor nearly gave up his eight remaining lives to cure her and Tegan, but thanks to the unlikely meeting of two Brigadiers, a substitute was found to cure her. Also, an undercover agent of the Black Guardian, Turlough, began traveling with them to escape exile on earth. (DW: Mawdryn Undead)

Nyssa left the TARDIS under circumstances as tragic and noble as the ones that had forced her into the Doctor's company. The TARDIS attached itself to a space liner when Turlough, still under the Black Guardian's influence, damaged its controls. The liner docked with what seemed to be a hulk floating in space, the Terminus space station. The Doctor and Nyssa discovered it was, in effect, a leper colony. She was the only TARDIS crew member who contracted the disease the station existed to treat. Just as she had always done with the tragedies in her life, she used her misfortune as a path to a better future. She chose to remain on the space station to help her fellow sufferers find a permanent cure for Lazar's disease. (DW: Terminus)

After her travels
Although she believed she would die — though in her words, "not easily" — on Terminus (DW: Terminus), Nyssa eventually left and settled down as an academic in a university on an unspecified planet. During this period, she encountered the Doctor's fourth incarnation again — long before he had first met her on Traken (PDA: Asylum). Eventually, she married and had children, the eldest a daughter, Neeka, with a man named Lasarti, who studied dreams. During this later period of her life, she reunited with the Doctor's fifth incarnation and again assisted with his regeneration into his next incarnation. (BFA: Winter)

Reunited with the Doctor
Fifty years after she left the Doctor, Nyssa was reunited with the Fifth Doctor, Tegan and Turlough on the planet Helheim while trying to find the cure for Richtes Disease which had claimed over six billion lives, then travelled with the Doctor again. (BFA: Cobwebs) During these later journeys in the TARDIS, she told Tegan that she was married and that she had two children, Tegan and Adric. (BFA: Heroes of Sontar) She also revealed that in her personal timeline she had already experienced the Fifth Doctor's problematic regeneration into the Sixth. (BFA: Winter) Thus, during this second period of travel with the Doctor, she had to keep her knowledge of the Fifth Doctor's end hidden from him. (BFA: Heroes of Sontar, et al) She was tempted to help intelligent rats create a non-lethal plague, in exchange for some tips in fixing the destablising Helheim cure (BFA: Rat Trap)

Personality
Nyssa seemed at once more mature and more naive than her fellow travelers. She did not brag of her scientific knowledge nor believe it made her superior. She faced the challenges of her adventures with determination and the 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". (MA: Goth Opera) Her trusting nature sometimes made her less alert to deception than Tegan (DW: Mawdryn Undead), but it also made her more adept at negotiating an effective balance between strong personalities. (DW: Earthshock, BFA: 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 Fifth Doctor's boyish idiosyncrasies.

She tended towards pacifism, though on one occasion she destroyed a Terileptil android (DW: The Visitation) and used the threat of violence to save the Doctor's life, shooting a pair of guards. (DW: Arc of Infinity)

Even though her world and her people were destroyed, she strove to live by their principles when she traveled with the Doctor. Nyssa was one of the Doctor's most intelligent companions and was one of the few capable of assisting with TARDIS operations.

Behind the scenes

 * Nyssa was originally meant to have appeared only in The Keeper of Traken as a supporting character. She was therefore the sole creation of writer Johnny Byrne, to whom royalties had to be paid when the character was used. Like the Brigadier and K-9, she is a rare example of a series regular to whom the BBC does not enjoy sole copyright.
 * In the Big Finish audio drama Cobwebs, the photo for Nyssa is a recent picture of Sarah Sutton, as this story is set fifty years after Nyssa's departure from the Tardis in Terminus.
 * Peter Davison was known to have preferred Nyssa over any of his other companions. He intervened on several occasions when John Nathan-Turner attempted to write the character out of the series.
 * Perhaps in deference to Davison's affection for Nyssa, Big Finish Productions greatly expanded Nyssa's roles. They have built a network of stories in the televised gap between Tegan's departure in Time-Flight and her return in Arc of Infinity which was very much greater than it appeared on television. Starting with The Land of the Dead, the Fifth Doctor began a long series of audio adventures with Nyssa as his sole companion.
 * Like Tegan, Adric and the Fifth Doctor, Nyssa was given a "costume" rather than a basic "look" by producer John Nathan-Turner. Nyssa's original costume narratively originated on Traken. It suggested her highborn status. It consisted of a maroon velvet jacket, a diaphanous, iridescent skirt, and multi-pastel, high-heeled shoes. It was accessorized with an ornamental hair comb and a wooly purse. This look persisted through the end of episode 2 of Castrovalva. However, long before this episode was filmed, it was determined the actor needed more practical clothing for the physical demands of her now-co-starring role. She exchanged her skirt for a pair of maroon trousers, lost the purse, and began wearing lower-heeled shoes. According to production notes on the DVD release of the preceding story, Logopolis, the second iteration of Nyssa's "royal Traken" look was inspired by a rehearsal in which actress Sarah Sutton wore Nyssa's top, but her own corduroy pants. She also lost her hair comb. She completely abandoned the "royal Traken" look in Snakedance, and changed her look every story until her departure in Terminus. Famously, her costume for her final story was mostly just the slip she had been wearing under her Mawdryn Undead dress.