The Polyphemus is an oil on canvas painting by the Italian Baroque painter Guido Reni, executed in 1639–1640, and housed in the Pinacoteca of the Capitoline Museum in Rome, Italy.

The Bolognese art historian Carlo Cesare Malvasia attributed such a painting to Guido Reni.

In Windsor Castle, there are two drawings signed by Reni, with dating of 1638 related to the figure of Polyphemus.

[2] The painting depicts the scene from the Odyssey where the blinded Cyclops, in anger starts to gather boulders to toss at the ships of Odysseus in the distance.

A more active depiction of the subject had been frescoed earlier in the Gallery of the Palazzo Farnese, at which Reni had worked under Annibale Carracci.