Answer
Fanny Minafer, played by Agnes Moorehead, is a pivotal character in "The Magnificent Ambersons." She is the ambitious and manipulative aunt of George Amberson Minafer, the protagonist. Fanny's scheming and cunning nature ultimately leads to the downfall of the Amberson family, as she manipulates events to secure her own financial and social position. Moorehead's portrayal of Fanny is both nuanced and chilling, capturing the character's complex motivations and ruthless determination.