2 of 18
George (T.R. Knight) and Izzie (Katherine Heigl), Grey's Anatomy
George and Izzie are a prime example of what can go wrong when two friends try to take their relationship to the next level. It's too bad it took creator Shonda Rhimes a few episodes to figure out what viewers knew all along: These two had absolutely no chemistry together. Plus: Shame on George for cheating on Callie!