The D20 Menace Manual is a listing of statistics for animals, aliens, and other potential enemies, for use in the D20 Modern role-playing game. It also contains various d20 conversions of monsters from the Alternity campaign setting Dark•Matter, including Mothfolk.

The book is divided into three chapters:

  • Monsters
  • NPCs
  • Factions

The monsters section consists of the supernatural foes of the book, such as aliens and demons. The NPCs section contains statistics for various ordinary people of various levels of skill. The factions section gives example groups for the heroes to face, ranging for terrorist organizations to recording companies. Some of these are more complete than others, showing how they could fit into premade settings and giving sample NPCs.