black hat(redirected from a black hat)
A villainous person, often such a character in a book or film. I'm pretty sure those black hats masterminded the heist—they are known for their lying and cheating.
black hat (or white hat)used in reference to the bad (or good) party in a situation.
This idiom refers to the colour of the hats traditionally worn by the bad (or good) characters in cowboy films.