Rain (portrayed by Tyrone Wiggins) is a minor character who appears in Mortal Kombat: Annihilation. He is a purple-clad ninja who serves Shao Kahn as a general, but does not fight at all in the film and dies early on. After letting two Earthrealm warriors live, Kahn punishes Rain by killing him, slamming the ninja with his iconic stone hammer and knocking him into a fiery red pit.
Rain is based off of a character from the Mortal Kombat games. His history is not explored in the film, but at the time the film was made his game counterpart's backstory had barely developed anyway.