The daughter of Consul Tremas of Traken, Nyssa joined the Doctor when the Master murdered her father, took over his body in The Keeper of Traken and finally destroyed her planet in Logopolis. She was very clever - bioelectronics was her forte - but her abiding belief in the goodness of all things blinded her to the more subtle forms of evil.

She was also gentle, quiet and rather serious, which meant that she sometimes failed to see the funny side. She left the TARDIS crew when she decided to stay on the planet Terminus, and help find a cure for Lazar's disease

Sarah's also reprised her role as Nyssa in some audio dramas for Big Finish and still goes to the conventions to meet fans