Prime-time television has become a killing field lately, with an unusual number of major characters kicking the bucket.

This TV season's final episodes were literal finales for some shows' main characters. Buffy the Vampire Slayer (search) and Dawson's Creek (search which both ended their runs — knocked people off, while Alias (search) and 24 (search) ended with the apparent deaths of a few of the majors.

"It was the season filled with carnage for regular characters," said Robert Thompson, director of Syracuse University's Center for the Study of Popular Television (search).

Thompson pointed to ratings and reality shows as the primary culprits behind the killings.

"What [reality shows] promise is something that scripted television hasn't been able to deliver," Thompson said. "They're able to vote off a character every week. That's one of the things that makes these shows so compelling. It's the equivalent of killing them off."

Shows like The Bachelor and Survivor have made viewers come to expect regularly scheduled big finishes — and have drawn boffo ratings, especially for their finales.

"The sweeps period has become so highly competitive that networks are pulling out all the stops to pull in viewers," said Kristin Veitch, a TV columnist for E! Online.

The WB's Dawson's Creek heavily promoted its last show with the warning that one of the four protagonists would perish. The finale scored high ratings as viewers tuned in to see bad-girl-turned-counselor Jen Lindley die of a heart ailment.

In the Buffy the Vampire Slayer finale, Buffy's love interest Spike and reformed demon Anya, plus several ancillary characters, died battling evil. CSI also saw the death of a recurring character, Detective Lockwood.

And on 24 and Alias, President Palmer and Francie may have each seen their last days.

While killing off characters wasn't as common in past decades as it is today, death has memorably befallen protagonists in shows including All in the Family, Dallas, M*A*S*H*, Hill Street Blues and Seinfeld.

But offing familiar characters used to be the exception. These days, the gimmick is on its way to becoming the rule.

"Dramas that wouldn't normally go into that realm are having to go down that route," Veitch said.

In that vein, major characters are being taken out even when the actors aren't having a contract dispute — which used to be the primary reason for eliminating familiar TV figures.

In Alias, a budgetary dispute led to an initial decision to kill two people in the finale, but because the issue wasn't resolved, the episode deliberately left things up in the air, Veitch said.

Even if there isn't a debate behind the scenes, the ambiguous endings are a perfect way to close a season.

"For shows that are coming back, the cliffhanger is a better way to do it, to keep people guessing all summer long," said Veitch. "It pulls in the viewer for the premiere next season."

Buffy fan Cristina Barden said that today's viewers have come to anticipate TV tragedies because of the recent real-life ones the world has witnessed.

"This is an indicator of the fact that we know bad things happen — we expect them, almost," Barden said. "Television always tries to have its finger on the pulse of society."

But Barden isn't a fan of the trend — and didn't love the macabre Buffy finale.

"I'm a great believer in happily ever after," she said. "Usually I want light, fluffy, tied up in a bow — totally unrealistic."

No matter what the motives, the death phenomenon isn't likely to go away, thanks to the mass ratings it tends to draw.

"People are expecting more of a payoff in the end," Thompson said. "There's nothing like knocking off a main character for shaking up the chemistry of the show."