Cowards are villains who are very prone to run away from a fight or confrontation or even their own problems, or who pick on those who they know are weaker or who have less authority (Hopper enslaves the ants because he "knows" that they are weaker than him; Pennywise/IT usually goes after kids because they don't know any better than adults).

They usually beg the hero to not kill them when overpowered by the hero and will try to kill them if they let their guard down, or are desperate to take the hero with them if they know that they are about to be defeated or killed (Gaston LeGume, Scar, Judge Claude Frollo and Frieza are excellent examples of this). More often than not, they would also threaten to kill the hero's loved ones or use them as hostages to stop the hero from attacking them, rather than fighting the hero themselves (Agnus and Sanctus are good examples for this).

Sometimes, being a coward motivates evil as they will do anything to save only their own hides and do not care if others get hurt (providing they don't get harmed themselves); other times, it serves as comedic relief while at still other times it simply makes a villain unlikable and/or weak in the eyes of a viewer or protagonist (and sometimes other villains as well).

They will also not hesitate to use cheap and dirty tactics if they deem it necessary to win a battle. Due to the fact that most Cowards will try to run away if they are in danger or even surrender entirely, they are rarely the leading antagonist (though exceptions do exist), tending instead to be bumbling sidekicks or henchmen. In addition, should these villains die, it is often disgraceful, unless they redeem themselves to die with honor.

But it can also make them seem even more heinous, considering they might just escape saving themselves and betraying others (e.g. Peter Pettigrew was made James and Lily Potter's secret-keeper, but he revealed their location to Lord Voldemort, resulting in their deaths).

Just because a villain is scared once doesn't make them a coward. For example, Patrick Hockstetter mentions how he isn't scared of anything at all, yet, he is scared of leeches. This doesn't make him a coward, as it is an understandable fear, and one of the only, if not the only thing he is scared of.

Additionally, bear in mind that Cowards can STILL be Pure Evil on certain circumstances, though they're not as cowardly as they seem and they can still prove to be a dangerous threat than any other cowardly villains, especially if they are left alone long enough by the heroes.