'Desperate Housewives,' 'Brothers & Sisters' Kick Off Week of Finales

season finales of 24 and LostFOX/ABC
season finales of 24 and Lost

Television addicts beware: 'tis the season for season finales.

Over the next two weeks, avid viewers will say goodbye to some of their favorite programs. "Lost" and "24" will be closing up shop forever, while other hits like "Grey's Anatomy" and "Modern Family" will go on hiatus for the summer.

To be sure you won't miss the latest investigation on "Law & Order" or the last dance on "Dancing with the Stars," here's a look at what to watch and when.

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SLIDESHOW: Top 10 Most Memorable TV Finales

Last night kicked off the first major night of season finales. "Desperate Housewives" went out with a bang -- Wisteria Lane newcomer Patrick Logan blew up himself with a bomb while serial killer Eddie helped deliver Lynette's baby. "Desperate Housewives" also introduced two plot lines for the coming season: a veteran nurse at the local hospital revealed, while dying, that one of Wisteria Lane's children was switched at birth and and old nemesis from the start of the show, Paul Young, showed up on the block again.

"Brothers & Sisters" wrapped up with a heart-wrenching finale. Rob Lowe's character, Robert McCallister, died in a multi-car pileup that involved almost all of the Walker clan. The same accident forced Uncle Saul to tell the family that he's HIV-positive, despite saying he tested negative for the disease earlier in the show.

But that was just night one -- there's plenty more drama and intrigue to relish as a crop of shows close their seasons this week:

"Grey's Anatomy" – Thursday, May 20

Promos for the season finale of ABC's medical drama "Grey's Anatomy" warn of a tragedy hitting Seattle Grace Hospital in the form of an armed gunman. Fans are hitting the blogs to discuss who the shooter might be and whether victims will be any members of the main cast.

Some are speculating that Dr. Meredith Grey, played by new mom Ellen Pompeo, may be the one to leave. But Pompeo has denied the rumors, saying only that she does not expect her contract to be renewed after season 8 of the program, which is still two years away.

On the show's website, the season finale's tag line is, "Who will fall?" The video of this week's episode shows doctors and nurses diving for cover as a gunshot is heard offscreen.

"Lost" – Sunday, May 23

The sixth season of this ABC drama will be its last, and television critics are expecting the four-and-a-half-hour season finale event to be epic.

"'Lost' is the big mother ship of season finales," said Matt Roush, a television critic at TV Guide Magazine. "It's like a Super Bowl event for fans."

"Lost" watchers are hoping that the season finale – the episode itself runs two and a half hours, with the rest taken up by show retrospectives – will finally explain why and how the characters found themselves on the same mysterious island.

"24" – Monday, May 24

If the true thrill-seekers have recovered from the marathon "Lost" event the night before, the next big finale to watch will be Fox's "24," which is another show that will not return next season.

Guide to TV's Season Finales

"The nights of the 23rd to the 26th are just completely insane," said TV Guide's Roush.

"24" is in its eighth season and fans are anxiously waiting to find out how Jack Bauer, played by Golden Globe-winning Kiefer Sutherland, will get to finish this long and grueling day during the two-hour series finale.

In a conference call with reporters earlier this month, the show's executive producer, Howard Gordon, warned that the finale isn't likely to be uplifting.

"This show's a tragedy, so to give Jack a happy ending didn't feel authentic," Gordon said.

Television critic Ray Richmond said that he's sure the series finale won't disappoint.

"'24' created a certain style of television, that heart-pounding, in-your-throat vibe," said Richmond. "I'm sure Jack Bauer will save the world one final time, and thank God for him."

"Law & Order" – Monday, May 24

After 20 seasons, NBC's "Law and Order" is finally throwing in the towel, but it isn't going off the air without a bang.

The final episode will feature Olympic gold medalist Lindsay Vonn, who has said that the show is one of her favorites.

According to a press release by NBC, Vonn will appear as a character named "Alicia," who is an administrative assistant with a clue in a terrorist case. The episode is titled "Rubber Room."

NBC also announced plans to pick up a new drama, "LOLA" or "Law & Order: Los Angeles," as well as renewing "Law & Order: Special Victims Unit."

"It had a very long and successful run and you can count on the fingers on one hand the number of shows that have gotten to 20 years," said Richmond. "It's kind of the end of an era."

"Dancing With the Stars" – Tuesday, May 25

The latter part of this week of season finales will be more light-hearted, starting with ABC's dance show "Dancing with the Stars."

The winning couple will be announced live during the 10th-season finale, starting at 9 p.m. ET.

Contestants who have been booted off so far this season include mother of eight Kate Gosselin and actress and model Pamela Anderson.

Other Finales of Note:

"Gossip Girl" -- Monday, May 17
"Modern Family" -- Wednesday, May 19
"30 Rock" -- Thursday, May 20
"The Celebrity Apprentice" -- Sunday, May 23
"CSI: Miami -- Monday, May 24
"The Good Wife" -- Tuesday, May 25
"The Biggest Loser" -- Tuesday, May 25
"Glee" -- Tuesday, June 8