LEADERS

The final test of a leader is that he leaves behind him in other men the conviction and the will to carry on. - - Walter Lippman

If leadership was a central theme to the drama of the show, how did the characters pass "the final test?"

Jack did leave Hurley in charge of the island. A very, very, very reluctant Hurley in charge of the island. But it is inferred that Ben was very "beneficial" in Hurley's island reign, so much so that Hurley was rewarded with heavenly reunion with Libby. (In the succession plan, that would leave Ben in charge of the island and sideways view, with the dual knowledge that only Eloise had).

Locke was only briefly in charge of the group when the time skips happened after Ben screwed things up in the FDW. However, Locke was a pawn in Christian smoke monster's plot to get Jack back to the island in order to thwart, kill Jacob to find MIB's alleged loophole (which may be the same as everyone else on the island - - - get to the sideways plane of existence, the after life, from the way station island).

Flocke was a more successful faux leader, who ruled like Ben and Widmore  did the Others, by an iron fist and no mercy. But Flocke was not a real human being, and he wanted to leave no one behind (as his mental state, if any, was to destroy all human candidates in order to escape his prison.)

Sayid was only briefly in charge of his Iraqi torture unit. But when push came to shove, he betrayed his uniform, killed a superior, let a prisoner escape, then became a U.S, CIA operative. On the island, Sayid refused a full leadership role (except on a few rescue missions) because he could not trust himself.

Sawyer was in charge of the beach castaways ("by default," as Hurley said) but that time Sawyer tried to "act" like a leader, but as a lone wolf con-man it was impossible for him to adapt. However, in the time warp arc, Sawyer did become a leader of his castway time travelers by becoming the sheriff of the barracks, waiting for the time skip to send them back. It was during this three year period that Juliet apparently tamed the wild Sawyer beast.

Kate led a few rescue missions, but tried to avoid becoming the leader of either the beach castaways or the candidates forum. She always put her own self-interests above other people. Even when she claimed to have "saved" Claire in the end by getting her on the plane, Kate could have stayed and gone back to try to save Jack, but she did not. She only wanted to get off the island. There were no tears in her decision.

Jacob was the leader who hid in the statue. He commanded through his liaison, Alpert, who in turn, gave instructions to Ben (who would twist things so he had the power.)  Alpert led the quiet Other near revolt against Ben, when he gave the file to Locke to make Locke the leader (by killing Cooper, his father, by Sawyer's hand.) Jacob assumed the leadership of the island at the request of his Crazy Mother, and regretted his actions that led to his own brother's demise (by the hands of the smoke monster). A leader with such guilt, shame and regret was never a good leader.

Widmore was a born bully of a leader. He was exiled from the island, and made his sole mission in life to return to recapture it. He used his inner strength to gather a vast fortune to fund his quest. In a certain respect, he succeeded at the task as he returned to the island, and indirectly defeated Flocke. But as a leader, he got blindsided by the vengeful rage of Ben, who killed Widmore for killing Alex. Many leaders find it appropriate to lead with "an eye for an eye" mission statement.

In their own way, and collectively, no one person was a great leader. Each had terrible personal faults and lacked command of their people and circumstances (which led to many lives lost.)