Re: Which movie would you use to introduce someone with Star Trek?
Most everyone I know who aren't Star Trek fans will watch Star Trek 4, it is a lighthearted place to start.
...though, when I first read your excellent thread idea, the first thing that popped into my holodeck addicted mind was series...depending on the age...for younger, I would start with TAS...for older, TOS...I know your thread asks for movies, but maybe something else to consider...
We live in a society exquisitely dependent on science and technology, in which hardly anyone knows anything about science and technology.
US astronomer & popularizer of astronomy (1934-1996)