Protagonist is the central figure of a story. Alternatively, the phrase denotes a primary advocate of or proponent for a cause or movement, that is, the character whose role makes the plot move further. As the main character is just the character with the main role, they can be either a hero or a villain in a story. However, main character villains are virtually unheard of due to the constraints of the character's category, with most characters in that vein falling under anti-hero instead. A protagonist is generally distinguished by a sympathetic portrayal, with even the most deplorable characters being made more relateable through the story's focus. In exceedingly rare circumstances, an author may subvert this and create a protagonist deliberately made to be unsympathetic.

Most Pokémon protagonists are a trainer character - a human boy or girl, at some age between ten and eighteen years old, who has at least one Pokémon 'partner', whether it be as a trained, wild, or non-standard Pokémon. Other stories focus on a Pokémon itself as the main character.

While stories can have a wide range of variation in the numbers of protagonists, most Pokémon stories tend have five or fewer protagonists. The opposite term to protagonist is antagonist.