|First Appearance||The Nightmare Begins|
Lawn Gnomes are statues of small humanoid creatures used to protect Zim's base. Their defenses include shooting lasers from their eyes and hands, seizing people, and assaulting them.
They are seen in almost every episode, and they also make a number of appearances in the comic series.
Their appearance is that of a normal garden gnome, but these machines have the capability to do serious damage to their victims.
As seen in "Future Dib", some or all of the lawn gnomes are capable of transforming into a menacing robot form with a aesthetic aspect that is much more Irken in design.
As seen in "The Girl Who Cried Gnome", some lawn gnomes act of their own volition, dragging intruders off the premises without command or simply dancing in circles. Presumably, they have some sort of AI consciousness.
Zim's lawn gnomes also appear to be abnormal in size, looking to be almost as tall as Zim himself.
However, it's notable that Zim is also exceptionally short.
Zim seems to have a great number of them at hand, many of them sitting dormant in his equipment room (as seen in "Rise of the Zitboy"). They can also sprout from the ground at any location, as seen in "The Girl Who Cried Gnome".
In Invader Zim: Enter the Florpus, they were first seen in the first act of the movie, attacking Dib as he was crawling to the base and then trying to defend himself, as it was implied that the gnomes were going to use their lasers on him. By contrast, when he later came back the gnomes were motionless.