Madame Merle is a character from Henry James's novel, "The Portrait of a Lady." She is portrayed as a sophisticated and worldly woman who plays a significant role in the life of the protagonist, Isabel Archer. Madame Merle is known for her charm and intelligence, often influencing the decisions of those around her. Throughout the story, Madame Merle's complex relationships and hidden motives are revealed, particularly in her connection to Gilbert Osmond and her impact on Isabel's choices. Her character embodies themes of manipulation and the consequences of social ambition, making her a pivotal figure in the narrative.