Gustav

"...and that's how, 150 years ago, your great-great-grandfather Gustav came to own this farm."

- Grandpa Dave

Gustav was the grandfather of Grandpa Dave, the great-grandfather of Jane Read, Jessica, Lucy, and Fred and also the great-great-grandfather of Arthur Read, D.W. Read, Kate Read, and Cora. He is only mentioned once, in Grandpa Dave's Old Country Farm. He bought the land in the town that Grandpa Dave's farm was on. Matthew could possibly be his brother.

Origin
According to his name he could be part Swedish which makes Arthur's maternal side of the family part Swedish.