We've talked about how Izzie's grief has been one of the central themes of Season 3 so far, and how actress Katherine Heigl (right) continues to warrant and draw rave reviews with a raw, emotional portrayal of the intern.

She may not have the most lines, but Izzie, in her response to the tragic death of Denny Duquette, is stealing the show.

Here's what the media and Katherine's own producers are saying about her efforts in last week's episode, "What I Am," and about her commendable achievement of playing a character enduring such heart-wrenching pain throughout the season:

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"Again, Katherine Heigl is amazing here. She sits, cradling the phone, tears silently streaming down her face. Katherine Heigl is doing such an excellent job making Izzie look lost and numb. It’s heartbreaking."

-- The Arizona Daily Star

"Katherine Heigl, in her quiet way, owned this episode: She didn't have so many lines, but has she ever been better? Something interesting and gloomy was washing over her face throughout the show. This was Heigl's best, most convincing grieving of the series."

-- Entertainment Weekly

"... This episode for me was really a chance to deal with the things that had been haunting me all summer. Especially Izzie. I’d been pretty worried about her, you see. She was in such pain when we left her. And let me tell you, I watched that final scene in Denny’s room where she wouldn’t get out of the bed more times than is probably normal for someone who WROTE the thing. I couldn’t help it -- Katie Heigl’s amazing performance sucks me in every single time."

-- Shonda Rhimes, Grey's Anatomy Creator & Executive Producer

"... I love Katie’s performance -- like she hasn’t slept in days. Like baking has replaced sleep and it’s all she can do to move her facial muscles and form words. 'Cause in my experience that is what it’s like when people you love suddenly die. I love that she’s not afraid to go there. You just don’t find that many beautiful actresses working in prime time TV willing to spend an entire episode without any makeup -- know what I mean?"

-- Krista Vernoff, Grey's Anatomy Producer & Writer

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.