Dimwits, or Idiots, are villains who rarely (if ever) use their heads. In other words, these villains are seen as stupid and simple-minded, and are very likely to foil their own plans or other villains' plans and can even cause them to ruin themselves; this is usually due to poor planning, stupidity, or bumbling. However, some of these villains (such as Beavis and Butt-head) can be viewed as being amoral, as they may not always be aware of their actions due to their stupidity.
This list does not apply to characters who are mentally challenged (such as Leatherface, Jason Voorhees, etc.), as there is a major difference between the two.
It is uncommon for a Pure Evil villain to be a dimwit, however in some cases their actions can prove to be too heinous and cruel that even they could get themselves harmed or worse (Hydell and Hidan for example). Purely Evil villains who fall in this category tend to be particularly brutal, vicious, or at least very impulsive, and they often require the assistance of more intelligent, or at least more collected, villains.