Of Manheim, Lancaster County, Sebastian Graff was born on March 22, 1744, the son of Sebastian Sr. and Eva (Weber) Graff. The son of a shopkeeper and merchant, he was naturalized in 1739. Graff served as director of the Juliana Library Company, 1784; was a member of the U.S. Constitution Ratification Convention; and was a charter member of the Senate of Pennsylvania. He married Catherine Jung. Senator Graff died in office during his second session on July 2, 1791.