'24'

Never before, and perhaps never again, will there ever be a show so singularly dependent on the cliffhanger concept than this hit program about federal agent Jack Bauer and his really, really bad days. What's most ironic, however, is that "24" has defied the definition of the word ever since its 2001 debut. Fans of the Kiefer Sutherland-starring show know that viewership comes with two promises: (1) Every episode will end with some dangling plot detail that will leave you hungering for next week and (2) everything will be wrapped up after that season's 24 one-hour episodes. At least that was the case for most seasons, until this past May -- now, Jack is back in the hands of the Chinese Consul, and "24" fans are holding their breath until the new season this January.

'Friends'

Technically, every season of this hit show ended with a cliffhanger except season two, but none tapped into the public consciousness quite like Monica's wedding at the end of season seven. While she prepares herself to walk down the aisle with Chandler (Matthew Perry), the other friends realize that the beau-to-be has vanished, and do their best to hide things. Meanwhile, Rachel (Jennifer Aniston) and Phoebe (Lisa Kudrow) find a positive pregnancy test and wonder who the lucky mother will be -- one of them, or is it Monica (Courteney Cox Arquette)? In the cliffhanger pantheon, it's the most memorable that any sitcom has ever cooked up.

'Dynasty'

Whatever "Dallas" would do, "Dynasty" would always try to do just a little bit better. It seems like a no-brainer, then, that instead of simply shooting one person, this drama about a Denver oil family took a whole mess of machine guns to a room filled with their cast. The coup in Moldova saw armed gunmen unleashing on the Carrington family wedding of Amanda and European Prince Michael, but, ultimately, the 1985 cliffhanger is most memorable for being one of the biggest gyps -- after months of wondering how many cast members would turn up dead, audiences were instead disappointed to learn that it was merely a minor character (Billy Campbell) and a guest star (Ali McGraw). 

'Star Trek: The Next Generation'

For sci-fi fans, few cliffhangers compare to the 1990 moment when Captain Picard (Patrick Stewart) was captured and turned into Locutus. The world was introduced to The Borg, and comparisons to the original series suddenly became much more credible. In real life, the plotline served as a valuable Plan B in case Stewart's soon-to-be-negotiated contract talks broke down. The months between seasons three and four saw Stewart's contract being renewed, Picard surviving the cliffhanger and countless newfound fans getting sucked in.

'Lost'

Over the last half-decade or so, the cliffhanger has gone from an occasional gimmick to something that feels almost mandatory for any drama -- and none in recent memory has been more effective than the mystery dropped on the island inhabitants of "Lost" at the end of their hugely successful first season. After much discussion of the mysterious hatch, Jack (Matthew Fox) and Locke (Terry O'Quinn) dynamite the door and peer inside, searching for everything from the behind-the-scenes maneuverings of their dilemma to the possible body of Jimmy Hoffa. What's inside there? Wouldn't you (and a couple dozen million other people) like to know.

'Buffy the Vampire Slayer'

It's a show that inspired some of the most loyal followers in TV history, so you might want to think twice before claiming that season five's cliffhanger, "The Gift," is anything less than sheer brilliance. Anyone outside the Buffy-zone will just start scratching heads over mentions of Summers' blood or the Buffy-Bot, so suffice it to say that Buffy (Sarah Michelle Gellar) makes the ultimate sacrifice at the end of the episode. After a brief glimpse of Buffy's gravestone, we're left pondering the bigger questions: Is death the greatest gift one can give? Does a tragic fate go hand-in-hand with the role of a hero? And most importantly -- how the hell will Buffy get herself out of this one?