Who are the characters of the boggart and the monster?

In "The Boggart" by Susan Cooper, the main characters include a mischievous boggart named the Boggart, who can shape-shift and create chaos, and the family who encounters it, particularly the children, Emily and her brother, who learn to understand and befriend the creature. The story explores themes of fear and acceptance, as the children discover that the boggart's antics stem from its loneliness and desire for connection. In contrast, "The Monster" from various folklore and literature often represents a fearsome and misunderstood being, embodying the darker aspects of human nature and societal fears.