The entire idea of Star Trek: The Next Generation wasn't ... According to an interview William Shatner gave in Starlog Magazine in 1987 [via Fandomwire], he wasn't enthused by the project, either.

Martha Hackett appeared in thirteen episodes of Star Trek: Voyager as a Maquis that was actually a Cardassian. Prior to that, she was in two episodes of Star Trek; Deep Space Nine as T'Rul.