I was thinking the other day, what are the foundational dogs for a breed in history? 

I think to make this as subjective as possible; there should be some requirements that the dog would need to meet to be considered foundational.  What are those requirements?  What defines a foundational dog? 

There is the hall of fame for sires and dames and that is a wonderful achievement, but not all of these dogs have had a major impact on the breed.

What in your opinion are foundational dogs in your breed?