William Sean McFly (b. April 1885) was the son of Seamus McFly and Maggie McFly, the father of Arthur McFly and the paternal grandfather of George McFly. He was the first McFly born in America. William did not take to strangers until Marty McFly under the alias of "Clint Eastwood" journeyed to 1885 and stumbled across their farm. "Wait, that was Great Grandpa Willie! I met him when he was a baby! He peed on me." —Marty, after just meeting an adult William