I noticed the first post on greatest QB was a hit, so let's try this with running backs.

Once again here is my top 5
1. Walter (Sweetness) Payton
2. Jim Brown
3. Barry Sanders
4. Emmitt Smith
5. Earl Campbell

Campbell was my favorite to watch. My dad has shown me many clips over the years of him taking on linebackers and just running them over. The greatest "power" back of all time.