Entertainment Tonight.

"Grey's Anatomy" fans have been waiting for Meredith Grey (Ellen Pompeo) and Derek Shepherd's (Patrick Dempsey) highly anticipated wedding -- but in a shocking turn of events on Thursday night another Seattle Grace couple walked down the aisle!

On the show's 100th episode it was Izzie Stevens (Katherine Heigl) and Alex Karev (Justin Chambers) who ended up tying the knot!

In an episode plagued by tragedy when a car accident claimed the lives of several graduating college students, and a new tumor is found in Izzie's brain, it was also filled with surprises and hope for the future.

"You never know the biggest day of your life is going to be the biggest," Izzie says during the show's opening. "It's the regular days the ones that start out normal, those are the days that end up being the biggest. Today was the wedding. It was beautiful, perfect."

Don't miss the season finale of "Grey's Anatomy" Thursday at 9 p.m. on ABC.