Here's the Invader Zim fonts. To install them to your computer so that you can use them, you must have an unzipping program such as WinZip or WinRar. Once you unzip it, save it to a temporary location. Then go to your Control Panel>Fonts then click on File>Install New Font and go to the directory you saved it in.

Irken- I created this font, so I feel special. It's with Irken Symbols as the alphabet. The rest, like letters and such are are all normal, because I didn't have what the Irken digits are.
Invader- I got this font from the forums at Wormbaby.com. It's the font used for titles of the episodes and stuff.