There can be only one.
Immortals fight the opportunity to be the only one, by cutting off each others heads. This is a great story of how one of the immortals, the highlander, from the clan McLead turns in to an immortal after being killed. He is then trained by Sean Connery to fight until there is only one.
This is just the first in a sequence of films which also led to a TV series.
Its an amazing film, but is slightly ruined by all the of films that follow offering a different creation story.
highly recommended.