A scoundrel is a person who does deliberately evil things. If your brother hides a fake mouse in your shoe and you therefore almost have a heart attack while getting dressed, you have every right to call him a scoundrel.
Though the term scoundrel isn’t used as much as it once was, it’s the perfect way to describe someone who breaks the law, has no morals, or someone like your sneaky sibling who loves to play practical jokes. Most villains in movies and on television can be put in this category. Interestingly, though women are quite capable of equally wicked behavior, this particular term is usually reserved for men.