10 Star Trek Actors Whose First Appearances You've Totally Forgotten
7. Diana Muldaur As Ann Mulhall
Diana Muldaur replaced Gates McFadden in The Next Generation's second season after she had fallen out with the production team. Dr. Crusher would return in the third season, whilst Dr. Pulaski would be the third and final Star Trek doctor that Muldaur would play.
The first was the astrobiologist Dr. Ann Mulhall in The Original Series episode Return to Tomorrow. Mulhall, Kirk and Spock are possessed by the non-corporeal beings of the planet Arret. The beings need the Enterprise team to construct them physical android bodies to house their essence. However, the promise of a physical form reignites the tension between the old enemies and Kirk, Spock and Mulhall nearly lose their lives.
One of Muldaur's best scenes is when, as the Thalassia possessed Mulhall, she attempts to convince Dr. McCoy to let her keep the form in exchange for Kirk's mind being returned. Faced with McCoy's refusal, she displays godlike powers in an attempt to intimidate him. It only leads her to realise just how dangerous regaining their physical form will be, and they resolve to return the Enterprise crews bodies back to them.
Muldaur doesn't appear in any future episodes and over twenty years later, it's easy to forget her earlier appearance!