Every tale, not just every script, requires at least three primary characters. You're now looking for films with less than three characters, and you'll be hard pushed to locate any. A character is any person or entity within the story who experiences events or changes during the course of the narrative. Short films usually feature only two characters: a boy and a girl. Sometimes another character is introduced but rarely more than that. Short films often focus on relationships between characters, including friendships and romances, so they require only two main characters. Short stories and novellas sometimes feature several characters. Film adaptations of these works tend to be too brief to include more than two protagonists. In general, then, a short film needs only two characters to tell its story.