Which animals have a special connection to humanity?

It is a well known fact that some animals have special connections with people. This is the case whenever animals have been hunting partners, guardians, or providers of needed services or products- such as milk and eggs. The species that are most commonly pets have often had such a special service role- be they cats that hunt out mice, and thereby protect the family's food, or the horse- which has born many a burden and greatly assisted in transportation of people and of goods.