Dr. William "Groundskeeper Willy" MacDougal (A.K.A. "G.K. Willington") is the groundskeeper of Springfield Elementary School. Scottish by ancestry, Willie's job is to supervise the children of the School during recess, and clean the halls. He is recognizable with his red hair and thick Scottish accent. He is often either a formidable enemy or an invaluable ally to Bart and Lisa.

Willy is physically muscular, and in one episode, he wrestles an Alaskan timber wolf.

However, Groundskeeper Willy is usually a villain, though almost always in Treehouse of Horror is a protagonist attempting to aid the primary protagonist(s), though is usually killed.

Willy is also often seen yelling at the kids for doing something minor. He often talks about his Scottish past before he came to Springfield, and actually claims to be from many towns in Scotland, including Glasgow, Loch Ness, and North Kiltown. In Lisa the Drama Queen, it is revealed that his name was "Dr. William MacDougal" before he came to America.

It seems Willie is homeless and mentally insane, as Skinner hired him after he escaped from an asylum. Nevertheless, Willie gets the job done, whether it may be crawling through vents to retrieve Santa's Little Helper or watching back school video tapes for Lisa's benefit.