In the William Golding novel, The Lord of the Flies, the tragic irony of Simon's death lays in the discovery of the beastie. Simon is the one who discovers the dead pilot and the parachute that when it billowed in the winds is what the boys thought was a beast. It was this perception of an unknown beast that lead to the increasingly chaotic attitude and behavior of the boys.
In addition, when Simon drags the parachute out of the jungle, the boys, are still in a primal frenzy after their first kill. When they see Simon and the parachute in the dim light, they do not recognize him. Thinking it is the beast, the boys attack Simon like animals, and they kill him with their hands and teeth.
So in reality it was Simon's discovery of the true nature of the "beast" that revealed who the real beasts were, and that discovery lead to his death.
As was mentioned in the previous post, the tragic irony attached to Simon's death concerns the true identity of the beast. Simon is the only boy on the island to realize that the beast is not a tangible being that exists, but is rather the inherent evil present in each person. After climbing to the top of the mountain and learning that the beast was actually a dead paratrooper, Simon runs to tell the boys. Unfortunately, Simon is murdered after he is mistaken for the beast. Golding describes the brutal murder by writing,
At once the crowd surged after it, poured down the rock, lept on to the beast, screamed, struck, bit, tore. There were no words, and no movements but the tearing of teeth and claws (219).
His depiction of Simon's murder portrays the boys as uncontrolled savages. Filled with bloodlust, the boys viciously attack Simon and attempt to tear him to pieces. At this point in the novel, the boys have entirely succumbed to their primitive nature and have abandoned all hope of civilization. They are savages who take pleasure in killing.