There are three classes of monsters: Humanoid, Beast, and Eldritch. Each monster belongs to one of these three types, indicated by the color on the monster marker. Humanoid monsters are blue, Beast monsters are brown, and Eldritch monsters are green. Each monster class has a matching combat deck of the same color that is used when the monster attacks or is attacked.
Occasionally, a certain scenario will involve a monster with a specific name and special significance to the plot of the story. These named monsters follow all normal monster rules, but must have a horror token placed on them to signify that it is a named monster. Named monsters are also immune to all effects that automatically kill a monster (such as Joe Diamond's "Lucky Break" ability.