Griffin is a surname of unrelated families. Both my mother and father came from unrelated Griffin families.
My mother's Griffin Family:
In England Griffin is often a place name meaning someone lived near, say, a pub with a picture of a griffin (the second most common animal in British heraldry).
My father's Griffin family:
In Ireland there are two major unrelated Griffin families, one (my father's) based around Waterford and Tipperary which migrated from Wales around 1100 AD as "Griffith" and changed the name to "Griffin" and a larger Griffin family centered around Kerry where Griffin is used as the anglicized form of a Gaelic name.
-- James Griffin, Forest Hills, New York