X-5
![](http://static.miraheze.org/dariawikiwiki/thumb/4/43/X-5.png/250px-X-5.png)
The X-5 Unit supervirus is a highly contagious bioweapon stolen by Dallas and Muddy Grimes in Beavis and Butt-head Do America. Beavis and Butt-head almost doom America to its ravages by accident but then (equally accidentally) save America - obviously good news for Daria Morgendorffer!
It occasionally turns up in Daria fanfics.