Who is hidden beneath the costume in the masque of the red death?

In Edgar Allan Poe's "The Masque of the Red Death," the figure hidden beneath the costume is the embodiment of the Red Death itself, a deadly plague. As Prince Prospero and his guests revel in their lavish masquerade, the appearance of this mysterious figure signifies the inescapability of death and the futility of their attempts to avoid it. Ultimately, the revelation of the figure serves as a powerful reminder that no one can escape their fate, regardless of wealth or status.