The Last Judgment was commissioned from Michelangelo by Pope Clement VII (1523-1534) shortly before his death. His successor, Paul III Farnese (1534-1549), forced Michelangelo to a rapid execution of this work, the largest single fresco of the century.
The first impression we have when faced with the Last Judgment is that of a truly universal event, at the centre of which stands the powerful figure of Christ. His raised right hand compels the figures on the lefthand side, who are trying to ascend, to be plunged down towards Charon and Minos, the Judge of the Underworld; while his left hand is drawing up the chosen people on his right in an irresistible current of strength. Together with the planets and the sun, the saints surround the Judge, confined into vast spacial orbits around Him. For this work Michelangelo did not choose one set point from which it should be viewed. The proportions of the figures and the size of the groups are determined, as in the Middle Ages, by their single absolute importance and not by their relative significance. For this reason each figure preserves its own individuality and both the single figures and the groups need their own background.
The figures who, in the depth of the scene, are rising from their graves could well be part of the prophet Ezechiels vision. Naked skeletons are covered with new flesh, men dead for immemorable lengths of time help each other to rise from the earth.
According to Vasari, the artist gave Minos the semblance of the Popes Master of Ceremonies, Biagio da Cesena, who had often complained to the Pope about the nudity of the painted figures. We know that many other figures, as well, are portraits of Michelangelo's contemporaries. The artists self-portrait appears twice: in the flayed skin which Saint Bartholomew is carrying in his left hand, and in the figure in the lower left hand corner, who is looking encouragingly at those rising from their graves.
You can view more details of the left side and right side of the fresco on the standard pages in WGA.