|Place of origin:||Earth|
|First seen in:||Prelude Nightshade|
|Other appearances:||PROSE: Nightshade, AUDIO: Nightshade|
|Main voice actor:||John Castle|
His elder brother, Maurice, had died by 1968 whereas his wife, Margaret, died in 1958. Trevithick's daughter, Paula, and her husband lived in the village of Crook Marsham, and Trevithick had planned to move in with them after his retirement. However, after he had sold his house, Paula and her husband were killed in a car accident in 1967. Their daughter had joined a hippie commune, and Trevithick ended up at Dalesview Retirement Home in Crook Marsham.
In December 1968, the Nightshade serials were rebroadcast on BBC2. Trevithick looked forward to becoming popular and famous again, if briefly. However, Crook Marsham was attacked by the Sentience, a formless alien hunger that devoured the villagers' life forces after appearing to them in forms taken from their memories. Trevithick became involved in the fight against the Sentience, which manifested to him in the form of the alien Insectoids from one of the Nightshade serials. Trevithick fought the Sentience several times, but when the Seventh Doctor's attempt to confront the Sentience at its lair failed, it took the form of the aliens to prevent their escape, Trevithick sacrificed himself to hold off the attacking "aliens" while the Doctor and Vijay Degun fled to safety. (PROSE: Nightshade, AUDIO: Nightshade)