Nothing like threatening to kill off your main character to boost a show to its best ratings of the season. Last night “Grey’s Anatomy” hit a season high and also became the highest-rated scripted show of the season by doing just that.

“Grey’s” averaged an 11.6 in adults 18-49, according to Nielsen overnights, 0.6 ahead of its previous best for September’s season premiere and 0.4 ahead of the 11.2 averaged by “House” earlier this month, the previous highest-rated scripted show.

It marked “Grey’s” second-best 18-49 rating ever, behind only last year’s post-Super Bowl edition. It was also the series’ second-highest-rated episode in 18-34s, averaging an 11.5.

The show also hit a season high in total viewers, 27.3 million, again trailing only last year’s Super Bowl show.

The big tune-in came courtesy of last week’s cliffhanger, which suggested that the show’s namesake, surgeon Meredith Grey, had flatlined after nearly drowning on the scene of a ferryboat disaster.

It was the finale of a three-part episode that has drawn increasing ratings each week, and it helped ABC become the first network to beat Fox this year on a night when the latter had a helping of “American Idol.”

“Idol” still did very well, dominating its 8 p.m. hour with the first of several Thursday night specials, but “Grey’s” rated higher. It was the first show airing on the same night as “Idol” this season to outdraw it in both 18-49s and total viewers.

The monster “Grey’s” boosted ABC to first among 18-49s with a 7.0 average rating and a 17 share. Fox was second at 5.9/14, CBS third at 5.1/13, NBC fourth at 3.5/9, Univision fifth at 2.6/6 and CW sixth at 0.9/2.
 
Fox started the night in the lead with a 9.0 rating at 8 p.m. for the first “American Idol” results show of the season. CBS was second with a below-average 4.6 for “Survivor,” NBC third with a below-average 3.9 for “My Name is Earl” (3.6) and “The Office” (4.2) and ABC fourth with a 3.2 for a repeat of “Grey’s.” Univision was fifth that hour with a 2.6 for the first hour of the music awards show “Premio Lo Nuestro 2007,” and CW sixth with a 1.2 for a “Smallville” rerun.
 
At 9 p.m. ABC took the lead in a big way with an 11.6 rating for “Grey’s,” the night’s top-rated show among 18-49s. CBS was second with a 6.7 for “CSI,” Fox third with a season-high 2.8 for the “O.C.” finale and Univision fourth with a 2.7 for its second hour of “Premio Lo Nuestro.” NBC finished fifth with a 2.6 average for “Scrubs” (2.8) and “30 Rock” (2.4) and CW sixth with a 0.7 for a repeat of “Supernatural.”
 
ABC led again at 10 p.m., this time with a very solid 6.2 for the first-ever “Oprah Winfrey Oscar Special,” bettering usual timeslot occupant “Men in Trees” by more than a third. NBC was second with a 4.0 for “ER,” CBS third with a 3.9 for “Shark” and Univision fourth with a 2.4 for another hour of “Premio Lo Nuestro.”
 
Among households, ABC led the night with an 11.4 average rating and an 18 share. CBS was second at 10.0/15, Fox third at 9.1/14, NBC fourth at 5.1/8, Univision fifth at 2.9/4 and CW sixth at 1.5/2.