a character not fully developed who seems to represent a “type” more than a real personality ( see also flat character)

an archetypal character that shows up again and again in story throughout the ages, fulfilling a universal purpose (such as a mentor character or comic foil to the protagonist)

A stock character is a fictional character that relies heavily on cultural types or stereotypes for its personality, manner of speech, and other characteristics. In their most general form, stock characters are related to literary archetypes, but they are often more narrowly defined. Stock characters are a key component of genre, providing relationships and interactions that people familiar with the work's genre will recognize immediately.