So, I’m writing this article so that later, I’ll have proof that I coined this term.
The Red Baron is something that is better explained through example.
Say you are writing a WWI story. Your protagonist is fighting the Germans, but the Germans are a faceless bunch and therefore not particularly exciting. To add tension, you invent a Red Baron-type character. You take ONE German, humanize him, give him a history, give him panache… and then make him really skilled and awful (no idea if the original Red Baron was evil, this is just an example). To your readers, the Red Baron becomes a stand-in for “the Germans”, and if the Red Baron is evil, all Germans become evil. By contrast, your protagonist becomes “good”, which helps to generate sympathy.
The Red Baron makes your story go from a hero fighting a nameless, faceless enemy, to a pitched battle between well-developed, gripping characters.
Now, there’s probably a literary term for what I’m describing. If there is, please leave the name in the comments. Otherwise, it shall be forever known as “The Red Baron”!
EDIT: Okay, forever is pretty damn short. Andrew LeBlanc shortened it to A Red Baron in this article, which is well worth reading. Now what are the rest of you waiting for? Let’s popularize this thing!