Space:1999 End of Eternity

In the *Space: 1999* episode "End of Eternity," the crew of Moonbase Alpha discovers an immortal alien named Balor, who has been imprisoned in an asteroid for centuries. Balor's immortality comes with a dark side—he thrives on causing pain and suffering. Initially, the crew is intrigued by Balor's knowledge and longevity, but they soon realize the danger he poses. Balor's sadistic nature leads to chaos and violence on the base. The crew must find a way to stop him before he destroys them all. The episode explores themes of immortality, the nature of evil, and the consequences of unchecked power.