|The Last Judgment
Last Judgment images are based first on Matthew 25:31-46 (cached): the Son of Man sits enthroned in Heaven and judges the nations, placing the saved on his right and the damned on his left. The former go off to Heaven, the latter to eternal punishment.
Further details come from I Corinthians 15:52 (cached): a trumpet sounds, and the dead arise incorruptible from their tombs (image). The latter detail, known as the Resurrection of the Body, is also attested by 1 Thessalonians 4:15-16 (cached) and the Apostle's Creed; it is a common element in larger Last Judgment images (example).
The same passage (4:16-17 in KJV) mentions an "archangel"; on the basis of this and the scores of references to angels in Revelation we usually see angels in attendance and conducting the souls to their respective destinations, as in the Conques and Autun tympana.
Some Last Judgments include the psychostasy -- St. Michael weighs the souls while devils try to interfere (example). In the early 12th century Last Judgment at Espalion, the presider in the psychostasy seems to be not Michael but a cat-like grotesque.
At left, a detail from the west tympanum at the Church of St. Foi, Conques, one of the most fully elaborated visions of the Last Judgment