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.