In his painting The Last Judgment, Michelangelo represents himself as a saggy sack of skin.

True. Michelangelo painted himself into the face of the saggy sack of skins.

Explanation:

The painting "The Last Judgement" by Michelangelo was commissioned by Pope Clement VII to depict Christ's Second Coming and the final judgement. This painting covered the whole altar wall of the Sistine Chapel in Vatican City.

The painting depicted Christ in the middle, and the righteous to his right while the condemned are on the left. Numerous historical figures also appear in the painting, one among which is that of St. Bartholomew who was a martyr. His death by being skinned alive became the manner of representation in the painting, though Michelangelo put his own face into that saggy bag of skin. In it, St. Bartholomew holds a knife in his right hand while a saggy sack of skin was held by the left hand, on which the face of Michelangelo was inserted by the painter himself.