Forbidden Planet (1956)

In director Fred Wilcox' influential, classic science-fiction space adventure - the first science-fiction film in color and CinemaScope - and an adaptation of Shakespeare's The Tempest - a forerunner of the entire Star Trek (and Lost in Space) franchises:

• the film's story - a journey by astronauts on a flying saucer-shaped United Planets space cruiser C-57D to a distant planet-star named Altair-IV with green skies, to investigate the fate of a colony planted 20 years before
• the first appearance of the film's real star -- friendly Robby the Robot (voice by Marvin Miller) (who influenced and was the progenitor of many other future robotic creations), functioning as both a house servant and guard, and providing comic relief: ("Sorry miss, I was giving myself an oil job!")

Robby the Robot

• the entrance of reclusive philologist Dr. Edward Morbius (Walter Pidgeon) - and his lovely, doe-eyed and very naive 19 year-old daughter Altaira (Anne Francis) who had never seen men - and upon seeing three crew members marveled: ("I've always so terribly wanted to meet a young man, and now three of them at once"), and who innocently asked after found swimming nude in a pool: ("What's a bathing suit?")
• Altaira's kissing scene with Lt. Farman (Jack Kelly) - and after a few moments, her comment that she couldn't feel any "stimulation" - and the creepy subtext of the film - Dr. Morbius' incestuous feelings for Altaira
• Morbius' tour of "Krell wonders", prefaced by his words: "Prepare your minds for a new scale of physical scientific values, gentlemen"; he showed some of the crew members a huge network of underground rooms, laboratories, deep shafts (composed of "78 hundred levels"), and cranium head-set devices that were reportedly the remains of an advanced technological and sophisticated civilization from 2,000 centuries earlier, inhabited by a mighty race of beings who called themselves the Krells: ("In times long past, this planet was the home of a mighty and noble race of beings which called themselves the Krell. Ethically and technologically they were a million years ahead of humankind, for in unlocking the mysteries of nature, they had conquered even their baser selves. And when, in the course of eons, they had abolished sickness and insanity, crime and all injustice, they turned, still in high benevolence, outward towards space....The heights they had reached, but then, seemingly on the threshold of some supreme accomplishment, which was to have crowned their entire history, this all but divine race perished in a single night. In the 2,000 centuries since that unexplained catastrophe, even their cloud-piercing towers of glass and porcelain and adamantine steel have crumbled back into the soil of Altair-4 and nothing, absolutely nothing, remains above ground")

Morbius' Tour of Underground Krell Labs

• the scene of the night attack on the crew of the flying saucer by the sinister, invisible Id monster - a living, giant biped monster with sloth-like claws, who killed some of the crew at the perimeter of a force field fence
• the scene of Morbius commanding Robby to kill Commander Adams (Leslie Nielsen) with a laser, and Robby's 'short-circuiting' - following one of Isaac Asimov's Three Laws of Robotics to never kill a human
• the ending sequence of Commander Adams confronting Morbius and demanding that he explain the Id ("What is the ID?"); at first, Morbius called the Id an outdated and obsolete term: "the elementary basis of the subconscious mind"; Adams warned about the Krell's shortsightedness: "But like you, the Krell forgot one deadly danger - their own subconscious hate and lust for destruction"; Morbius agreed and offered names for the invisible Id monster ("The beast. The mindless primitive! Even the Krell must have evolved from that beginning"); Adams continued: "And so those mindless beasts of the subconscious had access to a machine that could never be shut down. The secret devil of every soul on the planet all set free at once to loot and maim. And take revenge, Morbius, and kill!"; Morbius was slowly beginning to see that the Krell ("My poor Krell"), from 2,000 centuries earlier, didn't realize the power that was destroying them from within - when inner subconscious thoughts could be instantly realized; Morbius was reluctant to face the conclusion that he himself was "the living monster" when Adams became accusatory about him being the awakened monster: "You still refuse to face the truth...Morbius, that thing out there - it's you!"
• the realization in a startling confession by Morbius, that the Id was his own projected or externalized sub-conscious; Morbius explained that he was the source of the monstrous creature, after the Krell had built a machine able to release his inner beast; Morbius was forced to realize that he was unable to control his subconscious desires ("Guilty! Guilty! My evil self is at that door, and I have no power to stop it!")
• the concluding sequence of Morbius' instructions to explosively destroy the 'forbidden planet' of Altair (after triggering the machine's self-destruct mechanism, and due to detonate in 24 hours) to prevent its terrible technology from being used again
• Commander Adams' final assurances to Altaira (who was saved with the crew) as they watched the planet's destruction from afar in space: ("Yes, Alta, your father, my shipmates, all the stored knowledge of the Krell. Five seconds, four, three, two, one. Alta, about a million years from now, the human race will have crawled up to where the Krell stood in their great moment of triumph and tragedy. And your father's name will shine again like a beacon in the galaxy. It's true, it will remind us that we are, after all, not God")