Dare to be different: Star Trek II.
Most Star Trek movies have an underlying theme. Here's my take:
Star Trek I: Voyager comes home after learning so much about the universe that it becomes "intelligent". The theme is the possibility of artificial intelligence. But like all intelligent beings, Voyager searches for a purpose and does not believe it can answer that question without first finding its creator. Luckily for Voyager it finds its creator and moves on to a new plane of existence.
Star Trek II: (Favorite) Probably the most intellectually satisfying of the Star Trek series, the theme is of life and death in many forms. The movie opens with the Kobayashi Maru no-win simulation that sets one of two philosophic tones. Kirk, however, is the only man in Starfleet to have beaten the simulation. He did so by reprogramming the computers so it was possible to win. The other philosophic tone is "the needs of the many outweigh the needs of the few".
Older and battle weary, retirement/age is the no-win situation that Kirk now faces. When McCoy comes to visit "bearing Romulan Ale", his birthday feels like a funeral.
Luckily for Kirk, a vengeful Khan has managed to rescue himself from a planet that turned to dust and took the life of his wife. Survival on the barren planet was near impossible, but Khan also managed to beat the no-win scenario by staying alive and eventually getting off the planet.
A distress call returns Kirk to active duty. Now the two individuals who have never known failure - who have always found a way to win - will face each other. In so doing, they will meet life and death in different ways.
The Genesis project - how ironic - adds another dimension to the theme. In the Genesis Cave, Kirk learns of his adult son and, for a moment, thinks about a very different life he could have lived - and begins to feel really old. In leading Kirk to the Genesis pit itself, Carol comforts him, "let me show you something that will make you feel young as though the world were new".
Fast forward to the Motarin Nebula where both ships are equally vulnerable. The game is afoot with a fair stalemate between the two sides..."goose for the gander" - i.e., "the odds are even". Ultimately, with everything else being equal, Kirk, the more experienced man, wins...or does he?
Khan dies by his own hands by triggering the Genesis device inside his ship...his need for venegeance is overwhelming - the needs of the one outweigh the needs of the many.
Back at the Enterprise, warp speed is urgently needed to escape the Genesis perimeter. Seeing a no-win situation at hand, it's Spock's turn at the Kobayahi Maru. Spock, too, dies by his own hands, but for the opposite reason: the needs of the many outweigh the needs of the few (or the one).
Though the ship is safe, Kirk has never confronted death like this. The eulogy for Spock is especially heartwarming, "...of all the souls I have encountered in my travels, his was the most...human." Kirk is eventually at peace with the conflict between life and death, and recalls something Spock was trying to tell him, "it's a far far better thing I do now than I have ever done. It's a far better resting place I go to than I have ever known." The final words:
McCoy: "How do you feel?"
Kirk: "I feel young."
Gets me every time.
Star Trek III: Save the whales.