Joshua Douglas

 was a companion of the Third Doctor.

He stopped travelling with him after a disagreement over the fate of the Z'nai. (AUDIO: The Catalyst)

This final adventure was later briefly witnessed by the Fourth Doctor and Leela. (AUDIO: The Time Vampire)

Years later, while entertaining the Fourth Doctor and Leela, Douglas was killed by H'mbrackle. (AUDIO: The Catalyst)