Definition:

A person or character often against the protagonist (main character) and could also be called an opponent,enemy, rival and competitor.

Examples:

1) From the story "Peter Pan" by J.M. Barrie Captain James Hook is the antagonist as he always fights with Peter Pan.

2) From the story "The Three Little Pigs" by Joseph Jacobs the Wolf is the antagonist as he wants to eat the pigs.

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