Villains who win against the hero and/or are successful in at least one of their main ultimate goals.

They are, usually, the opposite of Incompetent villains (who do not succeed in anything), though some Incompetent villains CAN still be successful with a huge stroke of luck or with the help of much more competent evil-doers.

It should be noted that, for some, the goal wasn't to kill the main protagonist. Notably, Successful villains are very common in many modern-day horror movies in which many of these villains succeeded in killing the protagonist in the end.

In many works, a Successful villain can be a Protagonist since protagonists are known for winning in the end.

Though these two categories often overlap, this is not to be confused with Karma Houdini, as these villains, despite their success, can still be defeated later, usually at the end of the story if their success occurred at the beginning or middle of it, or in a sequel since some villain victories open the doors for sequels.