A spectacular antique marble group (Vatican Mus.) representing the Trojan priest Laocoön and his two sons being crushed to death by sea serpents as a divine punishment for warning the Trojans against the wooden horse of the Greeks; this incident is related most famously by Virgil in the Aeneid 2, 199–231 (according to another ancient source, Laocoön was punished rather for breaking priestly vows of celibacy). The sculpture has usually been dated to the 2nd or 1st century bc or the 1st century ad, although whether it is an original Hellenistic piece or a Roman copy has long been a matter of dispute. Pliny, who saw it in Rome in the palace of the future Emperor Titus (reigned ad 79–81), records that it was made by the sculptors Hagesander, Polydorus, and Athenodorus of Rhodes, and describes it as ‘a work to be preferred to all that the arts of painting and sculpture have produced’. This praise echoed long after the group had disappeared, and its rediscovery in a vineyard in Rome on 14 January 1506 caused a sensation, Michelangelo being among those who went to see it immediately. By June that year it had been bought by Pope Julius II (see Rovere) and displayed in the Belvedere Court of the Vatican, where it attracted countless admirers, becoming the most studied, copied, and discussed of all ancient works of art, outshining even the Apollo Belvedere and the Belvedere Torso. (As early as about 1530 the adulation it received was satirized in a woodcut—possibly designed by Titian—showing the figures changed to monkeys.) The Laocoön's intense emotionalism continued to be influential on Baroque sculpture, and in the Neoclassical age the work was given a new aesthetic significance by Winckelmann, who saw it as a supreme symbol of the moral dignity of the tragic hero and the most complete exemplification of the ‘noble simplicity and calm grandeur’ that he regarded as the essence of Greek art and the key to true beauty. G. E. Lessing took Winckelmann's remarks as the starting point of his book Laokoon (1766), one of the most influential of all aesthetic treatises. The sculpture's fame was embellished when it was one of the prizes taken from Italy by Napoleon (it was in Paris 1798–1815 before being returned to the Vatican). Subsequently the Laocoön's reputation as a work of art has declined, but although it is no longer considered one of the world's greatest masterpieces, it has slipped in esteem much less than some once-revered antique statues: it continues to be a work with a powerful hold over the imagination and still finds a place in almost all general histories of art.
The sculpture has been restored several times since its discovery, with missing parts supplied, and in 1960 what appears to be Laocoön's original right arm (found by chance) was returned to the figure (it is bent back towards his head, whereas the traditional arrangement has it stretched high above him). Shortly before this, study of the Laocoön was transformed when—in 1957—fragments of four groups of marble figures depicting events in Homer's Odyssey were found at Sperlonga, near Naples: the names Hagesander, Polydorus, and Athenodorus are inscribed on one of the fragments (which are now in the museum at Sperlonga), and the most impressive of them—a wild-haired head of Odysseus—is particularly close in style to the Laocoön. The marine grotto in which these sculptures were found was evidently used as a banqueting hall by the Emperor Tiberius (reigned ad 14–37); although he probably owned the sculptures, they (and by implication the Laocoön) were not necessarily made in his time (he could have inherited them rather than commissioned them). Nevertheless, many authorities now date both the Laocoön and the Sperlonga sculptures to this period—say c.25 bc–c.ad 25—and believe that Hagesander, Polydorus, and Athenodorus were high-class copyists producing virtuoso reproductions or adaptations of Greek originals for wealthy Roman patrons (the putative lost originals in these cases perhaps dated from the 2nd century bc). A recent theory (first made public in 2005) that the Laocoön is a forgery by Michelangelo has received little support. In 2006 an exhibition was held at the Vatican to mark the 500th anniversary of the sculpture's discovery, and in 2007 an exhibition entitled ‘Towards a New Laocoon’ was held at the Henry Moore Institute, Leeds, highlighting the work's continuing fascination for contemporary sculptors.