Who is on Star Trek

[pann_da_bear]

Today a Classic Trek ep is on, the one with the man from the future who is trying to save the planet, has a black cat with a shiny diamond collar, and stars Terry Garr, set in the past.

Anyway, I SWEAR that the character named "Seven" is using a sonic screwdriver - so I figure he must be a Doctor and Timelord ... who was Seven?

Curious ...