Lard Lad is a fictional mascot turned giant monster that appeared in the Simpsons Halloween episode "Treehouse of Horror VI".
He was originally an inanimate giant statue standing outside a doughnut shop but came to life after being struck by magical lightning and when Homer Simpson literally stole his gigantic doughnut (despite the fact the doughnut was likely inedible). Lard Lad became enraged at this blatant display of disrespect and pursued Homer - causing mass destruction in the process, while other large mascot statues around Springfield did the same as a result of the lightning storm.
Lard Lad also appeared as a major boss in The Simpsons Game (2007), where he was brought to life this time by Kang and Kodos and was defeated by Homer and Bart while Kent Brockman provided commentary. The level where Lard Lad is fought is humorously called "Shadow of the Colossal Donut".
Lard Lad as a giant monster is a parody of other monsters such as Godzilla and also likely was directly inspired by the Stay Puft Marshmallow Man, being a cartoon mascot that would be the last thing most people would ever think of as an evil monster.