Izzie Stevens (Katherine Heigl) runs some tests in a shot from "Life During Wartime," from Season Five of Grey's Anatomy.

Alex and Izzie care for a pained patient in "Life During Wartime," from Season Five of Grey's Anatomy.

Izzie Stevens sits on the back of an ambulance in "Life During Wartime," from the fifth season of Grey's Anatomy.

Alex and Izzie embrace in "There's No 'I' in Team" from the fifth season of Grey's Anatomy.

Yes she does. Quite a lot. Here she is in a photo from "There's No 'I' in Team," from Season Five of Grey's Anatomy. Dr. Stevens is never far from a new crisis.

Well, not that kind of action. But there's a lot of activity in this photo from "There's No 'I' in Team," from Season Five of Grey's Anatomy, as the residents discuss their respective days.

Cristina is always out to get ahead, and here she is up to her old tricks yet again in this photo from "There's No 'I' in Team," from Season Five of Grey's Anatomy.

Miranda barks orders at Izzie, Meredith, Cristina and Alex in this new promotional photo from "There's No 'I' in Team," from Season Five of Grey's Anatomy.

George and Izzie look a little tipsy in a photo from "Brave New World" from Season Five of Grey's Anatomy. Good to see them hanging out again!

Izzie Stevens looks adorable in pink in a photo from "Brave New World" from Season Five of Grey's Anatomy. Katherine Heigl is gorgeous - and not shabby as an actress by any means!

George and Izzie smile at each other in a photo from "Brave New World" from Season Five of Grey's Anatomy. These two used to be best friends, then hooked up, then broke up. What next?

George talks to Meredith and Izzie in a photo from "Brave New World" from Season Five of Grey's Anatomy. He has slept with both of them! Amazing.