Who is this tired looking Gnome, armed with a mason's trowel and reality-fixing plaster? Why, it's the Fourth-Wall Gnome! Just pay him no mind and pretend he doesn't exist. It makes his job easier. Always watching, and keeping an eye open for instances when the barrier between realities is damaged (like during Player Character-shenanigans) the Fourth-Wall Gnome is always there to fix the cracks in the wall; no matter how annoyed it makes him. After all, if he didn't do his job, who would?
Scholars hotly debate whether every sighting of the Fourth-Wall Gnome is the same individual, or if there's multiple of him. Additionally, some people believe him to be a lesser aspect of Garl Glittergold, tasked with keeping the fabric of reality from unraveling, and keeping an unknown force called "immersion" intact.