The cast of 'Grey's Anatomy'

Patrick Dempsey and Ellen Pompeo are snuggled in a rumpled bed, and he is looking at her. And by looking at her, we mean looking at her. It is the look that has sent several fictional lives on Grey's Anatomy into dramatic tailspins and has given millions of fans endless fantasy material.

And yet, Pompeo is...giggling. Hysterically.

She apologizes, but she cannot stop. A patient Dempsey morphs from smoldering leading man to bemused costar to, finally, stern taskmaster: ''Quiet, close your eyes, and breathe deeply.'' She does, and for a take or two, it works — Dempsey, as Dr. Derek Shepherd, can peacefully (well, except for the snoring) observe his lover, Dr. Meredith Grey, as she slumbers. Then her laughter breaks loose again, and Pompeo storms off the bedroom set, shouting, ''I can't work with him anymore!''

She is careful, later, to explain that this was just a joke (people are a bit sensitive around the set of the ABC hit these days). But emotions do run high — and fast — when it comes to Grey's Anatomy. Its myriad moods change from sexy to funny to dramatic to silly, making for an intoxicating thrill ride that is as unpredictable as it is unmissable.

Since their first half-season in 2005, Seattle Grace's improbably hot surgical staffers have gone from midseason replacements to bona fide stars. And now, having relocated to the toughest time slot on TV, Grey's has become nothing short of a phenomenon, luring an average of 21.4 million fans every week and consistently topping Thursday-night behemoth CSI in the 18-49 demographic. How did they do it? ''The characters are so human,'' ABC Entertainment president Stephen McPherson says. ''Life is messy, it's funny, it's tragic, it's dramatic, and this show captures that.''

For maintaining that deft dramatic balance, for performing a powerful emotional alchemy that transforms the hospital-show genre into something exciting rather than exhausted, and for casting perhaps the most telegenic assemblage of actors in the last decade — for all of these reasons, we have chosen the cast of Grey's Anatomy as our Entertainers of the Year. — Jennifer Armstrong

(To read the full cover story about Grey's, click here — and click through this gallery to see the other 11 folks who made our Entertainers of the Year list.)