The "sidekick stereotype" refers to the notion that a supporting character is secondary to the main protagonist, lacking depth and complexity. Synonyms for this stereotype include "hanger-on," "yes-man," "lapdog," "lackey," "flunky," and "minion." These terms all suggest a subservient and one-dimensional character who exists solely to serve the needs of the main character. Other related terms include "comic relief," which refers to a character who provides humor in an otherwise serious story, and "foil," which refers to a character who contrasts with the main character to highlight their strengths and weaknesses. Overall, these synonyms highlight the need for more diverse and well-developed supporting characters in literature and media.