As the years continue to pass, the legend of Star Trek IV: The Voyage Home continues to grow; the fact that it was not just a legitimate Trek film, but one of the better ones, becomes more astounding. When a mysterious probe shuts down Earth's defenses and power grids, emitting a strange signal, Captain Kirk (William Shatner) and his crew must find a humpback whale to answer the call.
That means traveling back in time to 1986 (before humpback whales went extinct). The chance to see Kirk and Spock (Leonard Nimoy) embrace the '80s culture is worth a viewing alone, but the crew's complete disregard for preserving the timestream makes the fact that they traveled back in time the least far-fetched aspect of the story.
It wasn't the last time the Trek series would have a brush with time travel, but it is by far the most memorable. Let's hope J.J. Abrams has plans for a remake.