Masters of the Universe (stylized as Masters of the Universe: The Motion Picture) is a 1987 American superhero film directed by Gary Goddard, produced by Yoram Globus and Menahem Golan and written by David Odell. It features Dolph Lundgren, Frank Langella, Jon Cypher, Chelsea Field, Billy Barty, Courteney Cox, Robert Duncan McNeill and Meg Foster.

It is based on the Mattel toy line of the same name and tells the story of two teenagers who meet He-Man, the most powerful man in the universe, and his friends, who arrive on Earth by chance from their home planet Eternia and go on a mission to save the universe from their enemies, Evil-Lyn and Skeletor. 

On the war-torn planet Eternia, the evil warlord Skeletor has seized control of Castle Grayskull, the center of power in the universe. His army has scattered the remaining Eternian defenders and Skeletor has captured the Sorceress of Grayskull, imprisoning her within a power-draining field and planning to seize power over the entire universe by the next moonrise. Skeletor's archenemies - the warrior leader He-Man, veteran soldier Man-At-Arms and Man-At-Arms' daughter Teela - rescue the Thenorian locksmith Gwildor from Skeletor's troopers. Gwildor reveals that Skeletor has acquired his invention: a "Cosmic Key" that can open a portal to anywhere by utilizing musical notes. The device was stolen by Skeletor's second-in-command, Evil-Lyn, allowing Skeletor to breach Castle Grayskull.

With Gwildor's remaining prototype of the Key in hand, He-Man and his friends travel to the Castle. They attempt to free the Sorceress but are overwhelmed by Skeletor's army and forced to flee through a hastily opened portal via Gwildor's Cosmic Key, transporting them to Earth. The Key is lost upon their arrival and discovered by two California teenagers - orphaned high school girl Julie Winston and her boyfriend Kevin Corrigan. While experimenting with the device, they accidentally transmit a signal that allows Evil-Lyn to track it. She then sends Skeletor's henchmen Saurod, Blade, Beast Man and Karg to recover it.

Kevin, an aspiring musician, believes the Key to be a new Japanese synthesizer and takes it to a music store run by his friend Charlie. Back at the school, Skeletor's henchmen arrive through a portal and chase Julie until she is rescued by He-Man, who is in search of the Key. The henchmen retreat to Grayskull where, incensed by their failure, Skeletor kills Saurod and sends the others back to Earth, with a larger force under Evil-Lyn's command. Back on Earth, Kevin returns to the school to find police investigating the damage caused by Skeletor's men, and no sign of Julie. Kevin is then taken to Julie's house by Lubic, a detective investigating the disturbance. They find no trace of her at the house, but Lubic is suspicious of the Cosmic Key, which he suspects Kevin may have stolen. Lubic confiscates the Key and leaves for Charlie's music store to verify Kevin's story. Immediately afterward, Evil-Lyn and her team break into the house and interrogate Kevin regarding the Key's location using a mind-control collar, before pursuing Lubic.

Julie and the Eternians arrive and release Kevin from the collar, then pursue Lubic and the Key. They arrive at Charlie's store, but Skeletor's forces catch up with them and a pitched battle ensues. Evil-Lyn recovers the Key and summons Skeletor to Earth. Skeletor's forces capture the Eternians and Julie is wounded by Skeletor's lightning blast, which simultaneously erases the memory storage of Gwildor's Key. He-Man surrenders to save his comrades and is returned to Eternia as Skeletor's slave. Skeletor attempts to torture He-Man into submission to make his victory complete, but He-Man refuses to yield. The moment arrives for Skeletor to receive the power of the cosmos and declare himself the Master of the Universe. He uses his new powers to attempt to force He-Man to kneel.

Back on Earth, Gwildor repairs the Cosmic Key and Kevin re-creates the tones necessary to create a gateway to Eternia. The group, including Lubic as he attempts to arrest them, are transported to Castle Grayskull, where they begin battling Skeletor's forces. Resenting that Skeletor absorbed the power of the Universe without sharing it with her, Evil-Lyn deserts him along with his other henchmen. He-Man retrieves the Sword of Grayskull and he and Skeletor begin a final battle, in which he shatters Skeletor's staff, restoring him to his normal state. He-Man offers mercy, but Skeletor draws a concealed sword and attempts to kill He-Man. As Skeletor lunges at him, He-Man knocks Skeletor into a vast pit below. The freed Sorceress heals Julie and Gwildor opens a portal to send the Earthlings home. Hailed as a hero for his bravery, Lubic decides to remain on Eternia.

Back on Earth, Julie awakens on the morning of her parents' deaths in a plane crash. Realizing the Key has transported her back in time, she prevents her parents from taking the ill-fated flight by taking their keys, then runs outside to find Kevin. He confirms that their experiences were real, producing a souvenir from Eternia: a small blue sphere containing a scene of He-Man in front of Castle Grayskull with his sword raised above his head.

In a post-credits scene, Skeletor's head emerges from the water at the bottom of the pit, saying "I'll be back!" 

 Dolph Lundgren as He-Man

    Frank Langella as Skeletor

    Courteney Cox as Julie Winston

    Barry Livingston as Charlie

    James Tolkan as Detective Hugh Lubic

    Christina Pickles as Sorceress

    Meg Foster as Evil-Lyn

    Chelsea Field as Teela

    Jon Cypher as Man-At-Arms

    Billy Barty as Gwildor

    Robert Duncan McNeill as Kevin Corrigan

    Anthony De Longis as Blade

    Tony Carroll as Beast Man

    Pons Maar as Saurod

    Robert Towers as Karg

    Peter Brooks as Narrator

    Richard Szponder as Pigboy