Simon is a leader in his ability to see the truth. Simon understands that a concrete beast does not exist but that the beast represents the evil in all of mankind and the fear that it breeds within society; the beast is man. He even attempts to voice this insight to the group within chapter 5, which shows his role as a leader; however, "Simon became inarticulate in his effort to express mankind's essential illness" (Golding 89). Simon's inability to assert himself within the group hinders his role as leader within the novel.
Jack is seen as a leader upon introduction, for he is introduced as the leader of the choirboys. He is even said to control them, and Piggy feels "intimidated by this uniformed superiority" from the very beginning (21). Jack's assertive nature and ability to take control is demonstrated when he volunteers to accompany Ralph and Simon on the first exploration of the island. He also develops as a leader in his ability to sway the boys under Ralph's leadership and provide an alternative group stemming from a desire to hunt and destroy.
Piggy truly is the brains behind Ralph's leadership on the island. He comes up with all of the ideas, such as calling the group together using the shell and taking names as a source of accountability; however, he is unable to carry out his ideas due to a lack in confidence and assertiveness.
Piggy is a leader by the example of his clarity and wisdom in the novel 'Lord of the Flies' by William Golding. Although portly and clumsy in his movements at the beginning of the novel, William Golding slowly and carefully develops Piggy's character so that we see that his comments are not always figures of fun - he shows true common sense and wisdom. Sometimes the other boys pretend to to denegrate his ideas and pour scorn on them, but then go on to implement them following his lead. He does not often get the credit for this though. His clarity of vision is represented by his glasses (we need glass to create heat for incendiary purposes in fire lighting) which of course get broken. This signifies the rejection of the prudent leadership he would have offered. This loss of a true friend and his wisdom is sadly reflected upon in the sorrowful musings by Ralph near the end.