Granddaddy is often used with affection to refer to one's grandfather. I cherish memories of baking cookies with my granddaddy.
Pro Tip 2/3
Southern Respect
In Southern US, 'granddaddy' can indicate respect for an older man, not necessarily a relative. Everyone in town looks up to Old Man Jenkins like a granddaddy.
Pro Tip 3/3
Cultural Family Role
Granddaddy can imply a wise family elder who offers guidance or historical knowledge. Ask your granddaddy about the family tree; he knows it all.