Immortal (Highlander)

An Immortal is one of a group of fictional characters seen in the movies and series of the Highlander franchise. Since they are immune to disease and stop aging after becoming Immortals, they can live forever and die only when they are beheaded.

The Immortals were first introduced in Highlander in 1986. They were created by script writer Gregory Widen who, according to Bill Panzer, producer of the Highlander franchise, "was a student at film school, and he wrote this as his writing class project. (...) He was apparently travelling through Scotland on his summer vacation and he was standing in front of a suit of armor, and he wondered, 'What would it be like if that guy was alive today?' And that's where everything fell into place — the idea that there are Immortals and they were in conflict with each other, leading secret lives that the rest of us are unaware of."

In the Highlander universe, the origin of the Immortals is unknown. Panzer states, "We don't know where they come from. Maybe they come from the Source." It is not known yet what the Source actually is. An attempt to explain the origin of the Immortals was made in the theatrical version of Highlander II: The Quickening (1991), which revealed that Immortals are aliens from the planet Zeist. This was edited out of the 1995 director's cut, Highlander II: The Renegade Version, in which the Immortals are from Earth, but from a distant past. Neither of the two versions is mentioned in later movies or the television series.

In either version of Highlander II, Immortals themselves do not know where they come from or for what purpose they exist. In Highlander, the Immortal mentor Ramírez, when asked by newly Immortal Connor MacLeod about their origins, answers, "Why does the sun come up? Or are the stars just pinholes in the curtain of night? Who knows?" In Highlander: Endgame, Connor MacLeod says, "We are the seeds of legend, but our true origins are unknown. We simply are." In the television series episode "Mountain Men", Duncan MacLeod expresses the same ignorance when he tells Caleb Cole, a fellow Immortal, "Whatever gods made you and me... made us different," and in his next line, deleted from the episode, he says, "They're just having a little fun."

...
Wikipedia