Charles Logan (Seasons 4-6) 4

Logan wasn't necessarily a likable character, but he is one that I feel was well played. Unfortunately his character seemed to change in each of the three seasons he took part in. In season 4 he is portrayed as a weak, unconfident individual when he quickly becomes President as a result of a tragedy. In season 5 he suddenly turns and becomes a cool, calculating mastermind of a plot to kill David Palmer. Then in season 6 he is a repentant man who is trying to redeem himself to his country. His character kind of suffers by the writers seasonal change in the character's demeanor. It was also pretty stupid in season 6 how he randomly appears, and then is dismissed from the show when he is stabbed by his ex-wife. His fate is left in the balance, as he may or may not be dead. The show never got around to explaining his fate.