Answer:
Samneric (the twins Sam and Eric).
Step-by-step explanation:
William Golding's "Lord of the Flies" revolves around a group of boys stranded on a deserted island and the struggle to be the leader. The novel explores the themes of human nature, the dark side of it, the loss of innocence, civilization, man's greed, and evil nature, etc.
The dead parachutist was first spotted by the twins, Sam and Eric while they were tending the signal fire. The author writes,
the figure sat, its helmeted head between its knees, held by a complication of lines. When the breeze blew, the lines would strain taut and some accident of this pull lifted the head and chest upright so that the figure seemed to peer across the brow of the mountain. Then, each time the wind dropped, the lines would slacken, and the figure bow forward again, sinking its head between its knees. So as the stars moved across the sky, the figure sat on the mountain-top and bowed and sank and bowed again.
It was this "dark figure" that Sam and Eric saw and assumed it to be "the beast".