An antagonist is a specific entity that continually stands in opposition to the protagonist or main character. Not all works of fiction include an antagonist, but many do. An antagonist may be an individual character or a group of characters. In Ken Kesey’s novel One Flew Over the Cuckoo’s Nest, the antagonist, Nurse Ratched, and the main character, a patient named Randle McMurphy, butt heads as McMurphy challenges Nurse Ratched’s authoritative and often dehumanizing power over the ward. An antagonist need not be human. In Stephen King’s novel Cujo, a rabid St. Bernard traps Donna and her son in their car. In Cormac McCarthy’s The Road, a novel that follows a young boy and his father in a harsh post-apocalyptic world, the bleak setting and the force of desperation that it spurs may be seen as the antagonist.

An antagonist is not always a villainous character. Some are downright kind. In Raymond Carver’s short story “Cathedral,” the narrator dreads the arrival of his friend’s wife, a blind man. The narrator is the story’s main character, but if anyone is unlikeable in “Cathedral,” it’s him. The blind man is the antagonist because his visit causes such unrest for the main character.

While your fiction doesn’t have to include an antagonist, it must have a series of compelling and persuasive obstacles that the main character must negotiate. What’s the difference? An antagonist is a specific presence that returns again and again throughout the fiction. Randle McMurphy always has to contend with Nurse Ratched in Kesey’s One Flew Over the Cuckoo’s Nest. In McCarthy’s The Road, the bleak setting and desperation is a constant threat to the young boy and his father.

Some fictions don’t have one main entity working against the character, but rather a series of them. In Joyce Carol Oates’ We Were the Mulvaneys, an idyllic family unravels after their daughter, Marianne, is raped. While the family struggles to heal, they are faced with many obstacles: the father’s inability to cope with his overwhelming anger and grief, the secrets they keep from one another and the mother’s choice to side with her husband over her daughter.

The antagonist is a compelling way to create formidable obstacles for the main character, but it’s not the only way.