I recently came across some people talking about the 80s, sci-fi/horror cult classic "The Hidden" and was reminded how much I enjoyed this flick.  Liked it when it first came out and still think it holds up.   

For those of you who don't know, it's a very different alien invasion movie.  An alien has landed and is indeed walking among us, "hidden" by disguising himself as a human  - but instead of working on some long-range plan to the planet, the alien is basically just out on a joy ride.  The film starts off with him speeding in a stolen sportscar while being chased by cops.  Earth weapons and dangers can't harm the alien - only the human host that he's hiding inside of.  The alien is difficult to track since he can leap out of the mouth of his current host and crawl into the mouth of a new one at any time. 

Kyle Maclachlan plays another alien out to capture the nasty one and defeats him with a special alien weapon before he can run for President in his current host. 

Once again, this is a very fun movie with a solid, original concept that's well executed.   In rethinking the movie, it became quite clear to me that the joy-riding alien might, in fact, not be fiction.  However, I don't think that the alien has been host-jumping that much, but instead has stayed within the same body for an extended period of time.  With this in mind, her actions over the years suddenly make a lot more sense to me....