5. Curtis Manning
Curtis Manning is one of the best characters in the history of 24; he was introduced in season four and soon enough earned the nickname "Blackjack Bauer", because of his similarities to Jack, and the belief among many fans that when Kiefer Sutherland eventually gave up the role, he would be the natural successor to take the crown. All the more frustrating it was, then, that he received such an extraordinary lame death at the hands of Jack, when Curtis was threatening to kill Assad at the start of season 6 (and believe me, this season didn't need help being the worst of the whole series). Jack ends up shooting Curtis in the neck, which kills him, much to the ire of many 24 fans who never understood why he couldn't have kneecapped Curtis or otherwise disabled him. It seems like such a hasty way to write a brilliant character out, such that I hope they essentially retcon the death and bring him back, even if it's as an antagonist. Hey, it worked for Tony, right?