Your great-grandfather is your parent's grandfather. He is the father of your grandparent, making him part of your family tree one generation above your grandparents. In terms of family relationships, he is considered your ancestor.
Your great grandfather!
He would be your paternal great grandfather
Your great great grandfather.
Your grandfather's great great niece is your second cousin, once removed
The great grandson of your great grandfather's brother is your third cousin
If your great great grandfather was the brother of someone else's great great grandfather then you and that other person are fourth (4th) cousins.
Your great grandfather's nephew was your grandfather's first cousin. You are two generations removed from your grandfather and his cousin. Therefore you and your great grandfather's nephew are first cousins, twice removed.
Your great grandfather's nephew was your grandfather's first cousin. You are two generations removed from your grandfather and his cousin. Therefore you and your great grandfather's nephew are first cousins, twice removed.
Your great grandfather's nephew was your grandfather's first cousin. You are two generations removed from your grandfather and his cousin. Therefore you and your great grandfather's nephew are first cousins, twice removed.
If the great grandmother of A is the aunt of B's grandfather, then A and B are third cousins.
Your aunt's great uncle's father is her great grandfather, or is not related to her at all if the great uncle married a sister of her grandfather).He would then be your great great grandfather - or not related to you at all.
Your great, great grandfather's son could be either your great grandfather or your great grand uncle, depending on whether his son was your grandfather or not.