OATER EXTRAS is a term used to refer to the additional characters in a western movie, such as a POSSE and gunmen. A POSSE is a group of people who are summoned by a sheriff or other law enforcement officer to help with a task, usually to search for a criminal or apprehend them. Gunmen are individuals who carry firearms and use them to threaten or intimidate others. OATER EXTRAS are often used to add tension and excitement to a western movie.