From Lexicanum

Xenos Horrificus is the Xenos's version of the stigma that can be bestowed on alien races deemed hostile or dangerous to mankind, and in need of exterminating. Each ordo has their own fancy High Gothic stigma.

• The Ordo Malleus declares a heretic Extremis Diabolus
• The Ordo Hereticus declares a heretic Hereticus Abomini
• The Ordo Xenos declares an alien race Xenos Horrificus

Those bearing a stigma must be hunted down and executed.

List of races declared Xenos Horrificus

• Lacrymole
• Zoats