A Villain Antagonist is when the villain and The Antagonist are the same person. This combination of roles is extremely common, to the point where the terms are often (falsely) assumed to be synonymous and used interchangeably, though probably not as much so as the inverse that often opposes this character, the Hero Protagonist. Simply put, the central character's opponent is also an established force for evil within the universe. This role is used most often in classical myths and heroic legends since these tales are usually a story of conflict between the forces of good and evil. It's common to see these characters either cause or be personifications of real-life issues in order to fulfill the audience's desire to see these problems dealt with when this character loses to The Hero. This character's primary role, generally speaking, is to provide conflict while giving the audience reason to root for the Hero Protagonist to win that conflict. Very common in almost any fictional story.
See Hero Antagonist and No Antagonist for notable exceptions of this trope.
