Although Nyssa was created by writer Johnny Byrne for the single Fourth Doctor serial The Keeper of Traken, the production team subsequently decided she should be retained as a continuing character.

She also encounters a race of androids and their insane ruler, helps foil the genocidal plans of a wounded Terileptil and incidentally starts the Great Fire of London, and discovers her uncanny resemblance to a 1920s English socialite Ann Talbot.

Later, they help Tegan battle her inner demons (personified by the Mara), and in the events of Mawdryn Undead they meet the Doctor's old friend and ally Brigadier Lethbridge-Stewart.

It is during this adventure that the TARDIS crew adopts Turlough, an alien posing as a pupil at an English boarding school, who has secretly entered into a bargain with the Black Guardian to assassinate the Doctor.

Nyssa's adventures with the Doctor come to an end here, as – to Tegan's horror – she elects to stay to help free the enslaved guards and turn the station into a real hospital.

[8] Although Nyssa's fate after the TARDIS is not certain, the spin-off novel Asylum by Peter Darvill-Evans, relates that she left Terminus and settled down as an academic in a university on an unspecified planet.

Since then Nyssa has appeared in several audio plays, still voiced by Sarah Sutton alongside Peter Davison as the Fifth Doctor, produced by Big Finish Productions.

The 'Winter' segment of Circular Time, by Paul Cornell and Mike Maddox, is set some years after Asylum and shows her with a husband, Lasarti, and a baby daughter, Nica.