Dimwits

Dimwits or Heroic Idiots are heroes who rarely (if ever) use their heads, have no intelligence, or even have no wisdom or common-sense at all (the former definition would be better classified as reckless). These characters are depicted as extremely ignorant, dim-witted, obnoxious, and are very likely to ruin their own plans. However, this is what they lack in the brain, they are more than making up for in the heart (well, most of them). These heroes follow very few or no orders mostly because they don't seem to understand a word that is said so they do the opposite of what is said without thinking.

However, some of these heroic idiots can be considered NOT particularly dim-witted nor ignorant, as some like Mordecai and Courage the Cowardly Dog can often be considered more careless, silly and sometimes, ignorant or feeble-minded as opposed to outright dumb. However, it is rare for idiots to reach the heights of characters like Patrick Star or Beavis & Butt-head in terms of stupidity.

The difference between intelligence and common sense is that intelligence is the ability to use knowledge to solve complex problems, whereas common sense is based on using judgement to deal with practical situations.

So there are characters who have good common sense, but are otherwise not very intelligent. Shonen heroes like Goku and Yusuke Urameshi are capable of being wise despite their lack of book smarts and general intelligence. Likewise, there are characters with high intelligence but have very little common sense. Geniuses like Jimmy Neutron and Dexter are highly bright but their lack of wisdom and foresight lead them to make utterly stupid decisions that gets them in silly and sometimes adverse situations.

This is a common trope, especially if it applies to the protagonist, known as Idiot Hero. Check out Idiot Hero on tv tropes.

Their evil counterparts are dimwitted villains, but it is also possible for an On & Off dimwit to have their stupidity lead them to commit acts so questionable that they cause controversy and can be interpreted as villains. Do not add these sorts of characters to Villains Wiki if their crimes are a result of them being more ignorant than malicious and they are not met with lasting infamy within the work (e.g. Homer Simpson and SpongeBob SquarePants). In order for a heroic dimwit to count as a villain, they must commit serious crimes and cause harm to the point where their insanity causes them to voluntarily become dangerous and malicious (e.g. Beavis and Butt-Head, Peter Griffin or Lumpy).

They still have the possibility of qualifying as Pure Good as long as their limited knowledge does not interfere with their moral agency, and the said hero meets all criteria.