What, if anything, might the dead parachutist symbolize?
The dead parachutist in Lord of the Flies symbolizes a link to the adult world. In the previous chapter, Ralph and Piggy wish desperately for a sign from the adult world:
If only they could get a message to us," cried Ralph desperately. "If only they could send us something grownup...a sign or something" (94).
That very night, the dead parachutist drifts onto the island. Yet in this story of decay and corruption, the boys' wish comes to them corrupted by the war in the Pacific, the adult they had wished for so vehemently is dead, and of no use to them. In fact, instead of being a comfort, the parachutist terrifies Samneric on the mountain. The twins see the billowing figure and mistake it for a beast. Only later does Simon realize the truth about the alleged beast, concluding that it is only a man. In the novel, Golding portrays the parachutist to represent the fall of man and his subsequent decay; in the end, he is only held together by the trappings of civilization, his harness and parachute.
The above answer make some good points. The boys on the island are not faring well and as the book progresses they will fare even worse. The base desires of their hearts will break down any semblance of order and civilization. Anarchy will rule the day. In light of this, the reader might think that what the boys need is adult supervision and intervention - adults will know better, right?
When the dead parachutist comes down, it is a sign from the world of the adults - a message from heaven, in a sense. But the message is not hopeful or helpful. In other words, if the boys need a role model or help from the outside world, they are in trouble. The war overhead (literally) shows that the adult world has problems as well.
Also the fact that the man is dead shows that the adult world cannot do much. To tie this passage into the theme of the beast, if the beast is within, then the beast is also within the adult world - a bleak note indeed.
The dead parachutist symbolizes the manifestation of evil on the island. The scene in which the paratrooper lifelessly drifts towards the island alludes to Lucifer's fall from heaven. Lucifer, also known as Satan, was once a high-ranking angel in heaven. He did not want to serve God but rather wished to be exalted above God. Lucifer's pride and ambition resulted in a heavenly battle where he and his followers were kicked out of heaven. Lucifer's fall from heaven corresponds with the paratrooper's descent to the island. Samneric are the first to spot the dead paratrooper and mistake the dead body for the "beast." The "beast" symbolizes the inherent evil each individual possesses on the island, which connects it to the allusion of Satan falling to earth. Satan and the "beast" both represent the impending evil on the island.