What does the masked figure represent in "The Masque of the Red Death"?
In one sense, the masked figure who crashes Prince Prospero's party is representative of the disease -- called the Red Death -- that ravages the kingdom. The disease is referred to as the Red Death because it is characterized by the hideous quantities of blood that seem to pour out of a person when they have contracted it. The narrator says of the disease, "Blood was its Avatar and its seal -- the redness and the horror of blood" because its victims would literally bleed from all their pores before they died. The masked figure comes, having "assume[d] the type of the Red Death." His clothes are "dabbled in blood -- and his broad brow, with all the features of the face, was besprinkled with the scarlet horror." He is the disease, personified.
However, the masked figure is more than just the disease. He can be interpreted as a symbol of death, in general, too. His mask looks like the face of "a stiffened corpse," and he is first seen by Prince Prospero as he stalks through the seventh room of black and red. This is the only room to be characterized by two colors, and so they both must be significant. Just as red is associated here, with the fatal disease, so black is often symbolic of death in general. Likewise, clocks are often symbolic of mortality and death, and so the ebony clock in this room provides another clue that anything associated with the room is likewise connected to death. It is not the Red Death, the disease, that holds "illimitable dominion over all" but rather death in general. No human, no matter their status, can escape death, though the prince clearly thought that he could. Thus, the masked figure represents both the bloody disease as well as death, generally speaking.
The figure you refer to in Poe's "The Masque of the Red Death" is death. There's no hiding from death, and it gets us all sooner or later.
The speaker describes the figure:
The figure was tall and gaunt, and shrouded from head to foot in the habiliments of the grave. The mask which concealed the visage was made so nearly to resemble the countenance of a stiffened corpse that the closest scrutiny must have had difficulty in detecting the cheat.
Habiliments are garments used to wrap corpses, and visage is the figure's face. In addition, the figure is splattered with blood, its brow "besprinkled with the scarlet horror."
The figure cannot be kept out no matter what is done to stop it, and in the end it kills everyone. The figure represents death.
Many would say that the masked guest who looks like death represents death itself. For example, the guests are afraid of the masked figure and they are also afraid of dying. No one has the "guts" to unmask the man. Also, no one can escape death; the guests attempted to "hole up" on Prince Prospero's mansion; however, they could not be protected from death because death finds all no matter race, ethnicity, age, religion, etc.:
The last line of the story indicates that the Red Death has triumphed over life: "And Darkness and Decay and the Red Death held illimitable dominion over all.’’ (eNotes)
It has a threefold meaning:
First, it represents the red death itself, infiltrating itself in the castle with no idea from the courtiers.
With this, another meaning is ascribed:
First, the inevitability of Fate- No matter how much they ran, they still were followed by the red death.
Second, the vulnerability of man- Again, as much as they tried to control a situation by sheltering themselves, it went and found them.
Third: Fate itself- The courtiers tempted it, and she got them- The illness appeared in the castle, as guarded and as sheltered from it as it was.