A Game Changer is a villain who appears in comedic or lighthearted media in which villains are meant to be friendly but creates a stark contrast by being played completely seriously and thus changing the tone of the story. To clarify, when a story portrays usually bumbling, comedic or incompetent villains or even villains who despite posing a conceivable and credible threat still have some comedic moments, the Game Changer is actually very competent, really dangerous, sometimes even frightening and has a much bigger impact. Episodes or stories featuring them focus on the seriousness and drama, and not on humor and comedy.

For a villain to qualify in this category, they must provide situations that are much more serious or threatening than any other villain that has appeared in the same story. The very appearance of only one alone can change the tone of the series for good and/or shatter the status quo. Game Changers are the the exact opposite of, and mutually exclusive from Comic Reliefs. They are also extremely rarely Incompetent or stupid, because such villains are very intimidating and dangerous threat.

Good examples for this are Isaac Ray Peram Westcott from Date A Live, Dennis from SpongeBob SquarePants, Dick Hardly from The Powerpuff Girls, King Sombra from My Little Pony: Friendship is Magic and Slade from Teen Titans who are seen as more competent than the rest of the villains.

Basic Guidelines:

1. They are hardly comedic. Of course, there are very rare exceptions, namely if their gimmick is that of a clown or jester in which that is simply part of their gimmick. This cannot distract or lighten the mood.
2. This is not simply a dark character. It has to be of an unheard level of villainy, like a Serial Killer in My Little Pony or similar very lighthearted media.
3. There are very few, if any of these within a story or said media, and if you have had one before it is much harder to have another one later due to a couple of reasons. After one is introduced, it is harder for another villain to stand out enough to truly count. The other reason is that the audience in general isn't as easily shocked and at times even expect more like them.
4. This villain type must ultimately contrast to the current setting of the story and, by just their very presence darken it as a result. This feels strange and is previously unheard of within the setting