The Red Death And The Holy Spirited One By Michael

Me: For this entire poem, instead of imagining the figure in question as being death, imagine instead that this figure is someone who is 'holy spirited' and that this one person can effect the whole party so devastatingly that pretty much everyone trapped inside "died" so to speak.

Me to Google Gemini: show me the poem the red death and who its by, masked people at a party and any one of them could be death

Google Gemini: 

It sounds like you're referring to "The Masque of the Red Death" by Edgar Allan Poe.

This is not a poem, but a very famous short story. It absolutely features masked people at a party, and the terrifying premise that one of them is Death itself, or rather, the embodiment of the plague.

Here's a brief summary of the story and why it fits your description:

Title: "The Masque of the Red Death"

Author: Edgar Allan Poe

Year Published: 1842

Story Overview (focusing on your description):

Prince Prospero, a wealthy and eccentric ruler, retreats to a secluded, opulent abbey with a thousand chosen guests to escape a deadly plague sweeping the land, known as the Red Death. He seals them all inside, believing they can avoid the pestilence outside.

After several months of isolation, Prospero hosts a grand masked ball. The revelry takes place in a suite of seven distinctly colored rooms, each more bizarre than the last, culminating in a black room with blood-red windows, containing a giant ebony clock that chimes ominously every hour, momentarily silencing the festivities.

During the height of the ball, a tall, gaunt figure appears, dressed in the grave-shrouds of the dead, with a mask resembling the rigid countenance of a corpse, and features splattered with the "scarlet stains of the Red Death." This figure's appearance is so horrific and disrespectful that it chills the merriment.

The Key Point to your query ("any one of them could be death"):

The masked figure is not just another guest; it is the personification of the Red Death itself. It has infiltrated the sealed abbey and Prospero's seemingly impenetrable sanctuary. When Prospero finally confronts this figure, he dies, and one by one, all the revelers fall, succumbing to the plague inside their supposedly safe haven.

The story is a chilling allegory about the inevitability of death, and how no amount of wealth or isolation can truly escape it. The "masked people at a party" are the revelers trying to escape, and the ultimate "Death" is among them, albeit a singular, terrifying entity that appears at the climax.