Willie is from Northkilttown, Scotland. His past is vague, but we do know that his father was hung for stealing a pig. Eventually he came to America and found work as a groundskeeper for a school. He lives in a shack on the grounds. Willie has never really down anything with his life, though once he is made to be a gentleman, by Lisa Simpson. Willie is a strong lad. He often fights people, when he's not yelling at them. On one occasion he is greased up and sent into the school vents to get a dog. He catches the pup and remarks that no animal can outrun a greased Scotsman.
Apparently, Willie lost some of his hearing but claims that he can read lips.