In Stargate SG-1, a television series based upon the 1994 science fiction movie Stargate, Jaffa is a race.
Jaffas are aliens, whose home planet is called Chulak. Their main function is to serve their gods, the Goa'ulds. They learn to fight very early in their life.
At a given age, an immature Goa'uld larva is implanted in their abdomen. Then, they act as incubators.
The presence of the larva removes the Jaffa's Immune system. But in exchange, the Goa'uld offers him strength and long life. (about 2 hundred years) The larva is able to treat the Jaffa's wounds very quickly.
Christopher Judge plays Teal'c, a Jaffa who chose to join SG-1 team and fight for freedom.