Drugs on TV have had a strange history. There have been after-school movies, very special sitcom episodes and even entire dramas based around illegal substances.

Sometimes, drug abuse on TV is used to teach the audience a lesson, while other times writers have characters develop an addiction as a way of making them more human in a flawed sense.

One of the most recent drug abusers comes to us in the form of Edie Falco's title character on 'Nurse Jackie.' The medical drama is back with a vengeance (Mon., March 22 10PM on Showtime), and to celebrate the return of our favorite no-nonsense RN, we're taking a look at TV's other famous pill-popping characters we've come to love (despite their issues) over the years.

We're not endorsing drug abuse of any kind, but it's a fact of life for some people, including these TV characters.

Find out who made our list after the jump.

Over the weekend, the Wall Street Journal wrote an article pondering the demise of The O.C. It lost 26% of its audience when season two started up. Then 15% more disappeared (myself included) for season three. And, now in season four, The O.C. lost a whopping 39% of its crucial, age 18-49 viewers from last season. It's in so much trouble that the network has even launched an online effort to save the show. (Or gauge viewer interest)

Why?

The article includes a very frank interview with The O.C. creator, Josh Schwartz, who admits some mistakes. He says, opening up the series during season two to include storylines for the parents was too much to juggle. When it started to get stale, he killed off Caleb Nichol. Smart move, he says. But, he wonders whether it was such a hot idea to kill off Marissa Cooper's character at the end of last season.

. . . twelve killed-off characters

Nothing says Christmas like the mention of a dozen (or so) characters that met their maker this past year. Here they are, in no particular order.

• Ellen Tigh, Battlestar Galactica -- Ellen meant well, of course . . . sleeping with one of the Cylons occupying New Caprica to ensure the safety of her husband Saul. But, she went too far to keep her husband safe and paid for it with her life. To make it even worse, Saul was the one who killed her by having her drink a beverage filled with poison.

America's favorite troubled teenager might be walking away from her job. Rumors are flying that Mischa Barton has had enough of her role as Marissa Cooper on The O.C.

Supposedly, Barton is worried about being type-cast as well as the show's mediocre ratings. I suppose I can't blame her for being ticked off about the ratings. Stacking this show (any show for that matter) against CSI is going to hurt eventually. I guess we'll just have to wait and see how this season ends. It'll be weird if Marissa is involved with any sort of cliffhanger only to be absent when the next season rolls around. If she does leave, the show just won't be the same. Anyone think it would work without her?

[via UPI]

Tonight was the triumphant return of Kaitlan, Marissa's once invisible sister turned jailbait sister. Awww, the magic of TV speed-aging. When last we saw Kaitlan, she was wearing pink sweatsuits, and complaining about not getting to ride her hairless pony enough. All the while, her older sis was overdosing in Tijuana, and almost being raped by her boyfriend's brother. Yup, it's about time for Kaitlan's return.