Which saint's flayed skin in The Last Judgment is believed to be Michelangelo's self-portrait?

Saint Bartholomew’s flayed skin in Michelangelo’s Last Judgment is widely believed to contain a self-portrait of Michelangelo.

In the fresco, Saint Bartholomew appears beneath Christ, holding the attribute associated with his martyrdom: his own skin. The face painted on that limp skin is commonly identified as Michelangelo’s, creating one of the work’s most startling and personal details. The saint’s living face and the face on the skin are deliberately different, supporting the idea that the skin functions as a separate portrait.

The fresco was painted on the altar wall of the Sistine Chapel between 1536 and 1541. Bartholomew’s martyrdom traditionally involved flaying, so the unusual object is an iconographic clue rather than an arbitrary gruesome addition. Michelangelo may have used the image to express spiritual exhaustion, self-doubt, or the hope of shedding the bodily self.

The identification is an interpretation rather than a signed fact recorded by Michelangelo. Most later writers accept it, but other proposed self-portraits have also been suggested elsewhere in the fresco. The saint himself is not Michelangelo; the supposed likeness appears on the flayed skin he holds.